{"id":60578,"date":"2026-01-15T22:57:16","date_gmt":"2026-01-15T14:57:16","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/60578.html"},"modified":"2026-01-15T22:57:16","modified_gmt":"2026-01-15T14:57:16","slug":"mysql%e5%a4%8d%e5%90%88%e6%9f%a5%e8%af%a2","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/60578.html","title":{"rendered":"MySQL\u590d\u5408\u67e5\u8be2"},"content":{"rendered":"<\/p>\n<h4>\u6587\u7ae0\u76ee\u5f55<\/h4>\n<ul>\n<li>\u4e00\u3001\u524d\u60c5\u56de\u987e<\/li>\n<li>\u4e8c\u3001\u591a\u8868\u67e5\u8be2<\/li>\n<li>\u4e09\u3001\u81ea\u8fde\u63a5<\/li>\n<li>\u56db\u3001\u5b50\u67e5\u8be2<\/li>\n<li>\n<ul>\n<li>1.\u5355\u884c\u5b50\u67e5\u8be2<\/li>\n<li>2.\u591a\u884c\u5b50\u67e5\u8be2<\/li>\n<li>3.\u591a\u5217\u5b50\u67e5\u8be2<\/li>\n<li>4.\u5728from\u5b50\u53e5\u4e2d\u4f7f\u7528\u5b50\u67e5\u8be2<\/li>\n<\/ul>\n<\/li>\n<li>\u4e94\u3001\u5408\u5e76\u67e5\u8be2<\/li>\n<\/ul>\n<p>\u5728\u524d\u9762\u8868\u7684\u57fa\u7840\u4e0a\u8fdb\u884c\u64cd\u4f5c&#xff1a;<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">show<\/span> <span class=\"token keyword\">tables<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> Tables_in_scott <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> dept            <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> emp             <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> salgrade        <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">3<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token operator\">*<\/span> <span class=\"token keyword\">from<\/span> dept<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> dname      <span class=\"token operator\">|<\/span> loc      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">40<\/span> <span class=\"token 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comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> empno  <span class=\"token operator\">|<\/span> ename  <span class=\"token operator\">|<\/span> job       <span class=\"token operator\">|<\/span> mgr  <span class=\"token operator\">|<\/span> hiredate            <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> comm    <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007369<\/span> <span class=\"token operator\">|<\/span> SMITH  <span class=\"token operator\">|<\/span> CLERK     <span class=\"token operator\">|<\/span> <span class=\"token number\">7902<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1980<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">12<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">17<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">800.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007499<\/span> <span class=\"token operator\">|<\/span> ALLEN  <span class=\"token operator\">|<\/span> SALESMAN  <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">02<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">20<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1600.00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">300.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007521<\/span> <span class=\"token operator\">|<\/span> WARD   <span class=\"token operator\">|<\/span> SALESMAN  <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">02<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">22<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">500.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007566<\/span> <span class=\"token operator\">|<\/span> JONES  <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span> <span class=\"token number\">7839<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">04<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">02<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007654<\/span> <span class=\"token operator\">|<\/span> MARTIN <span class=\"token operator\">|<\/span> SALESMAN  <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">09<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">28<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1400.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007698<\/span> <span class=\"token operator\">|<\/span> BLAKE  <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span> <span class=\"token number\">7839<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">05<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">01<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007782<\/span> <span class=\"token operator\">|<\/span> CLARK  <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span> <span class=\"token number\">7839<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">06<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">09<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2450.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007788<\/span> <span class=\"token operator\">|<\/span> SCOTT  <span class=\"token operator\">|<\/span> ANALYST   <span class=\"token operator\">|<\/span> <span class=\"token number\">7566<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1987<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">04<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">19<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007839<\/span> <span class=\"token operator\">|<\/span> KING   <span class=\"token operator\">|<\/span> PRESIDENT <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">11<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">17<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007844<\/span> <span class=\"token operator\">|<\/span> TURNER <span class=\"token operator\">|<\/span> SALESMAN  <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">09<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">08<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1500.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token number\">0.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007876<\/span> <span class=\"token operator\">|<\/span> ADAMS  <span class=\"token operator\">|<\/span> CLERK     <span class=\"token operator\">|<\/span> <span class=\"token number\">7788<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1987<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">05<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">23<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1100.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007900<\/span> <span class=\"token operator\">|<\/span> JAMES  <span class=\"token operator\">|<\/span> CLERK     <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">12<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">03<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">950.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007902<\/span> <span class=\"token operator\">|<\/span> FORD   <span class=\"token operator\">|<\/span> ANALYST   <span class=\"token operator\">|<\/span> <span class=\"token number\">7566<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">12<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">03<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007934<\/span> <span class=\"token operator\">|<\/span> MILLER <span class=\"token operator\">|<\/span> CLERK     <span class=\"token operator\">|<\/span> <span class=\"token number\">7782<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1982<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">01<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">23<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1300.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">14<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token operator\">*<\/span> <span class=\"token keyword\">from<\/span> salgrade<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;-&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> grade <span class=\"token operator\">|<\/span> losal <span class=\"token operator\">|<\/span> hisal <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;-&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">1<\/span> <span class=\"token operator\">|<\/span>   <span class=\"token number\">700<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">1200<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">2<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">1201<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">1400<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">3<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">1401<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">2000<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">4<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">2001<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">3000<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">5<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">3001<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">9999<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;-&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token number\">5<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.01<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<h2>\u4e00\u3001\u524d\u60c5\u56de\u987e<\/h2>\n<ul>\n<li>\u67e5\u8be2\u5de5\u8d44\u9ad8\u4e8e500\u6216\u5c97\u4f4d\u4e3aMANAGER\u7684\u96c7\u5458&#xff0c;\u540c\u65f6\u8fd8\u8981\u6ee1\u8db3\u4ed6\u4eec\u7684\u59d3\u540d\u9996\u5b57\u6bcd\u4e3a\u5927\u5199\u7684J<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token operator\">*<\/span> <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> <span class=\"token punctuation\">(<\/span>sal <span class=\"token operator\">&gt;<\/span> <span class=\"token number\">500<\/span> <span class=\"token operator\">||<\/span> job <span class=\"token operator\">&#061;<\/span> <span class=\"token string\">&#039;MANAGER&#039;<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">and<\/span> ename <span class=\"token operator\">like<\/span> <span class=\"token string\">&#039;J%&#039;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> empno  <span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span> job     <span class=\"token operator\">|<\/span> mgr  <span class=\"token operator\">|<\/span> hiredate            <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> comm <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007566<\/span> <span class=\"token operator\">|<\/span> JONES <span class=\"token operator\">|<\/span> MANAGER <span class=\"token operator\">|<\/span> <span class=\"token number\">7839<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">04<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">02<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007900<\/span> <span class=\"token operator\">|<\/span> JAMES <span class=\"token operator\">|<\/span> CLERK   <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">12<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">03<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">950.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">2<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">1<\/span> warning <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p>\u6216\u8005<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token operator\">*<\/span> <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> <span class=\"token punctuation\">(<\/span>sal <span class=\"token operator\">&gt;<\/span> <span class=\"token number\">500<\/span> <span class=\"token operator\">||<\/span> job <span class=\"token operator\">&#061;<\/span> <span class=\"token string\">&#039;MANAGER&#039;<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">and<\/span> substring<span class=\"token punctuation\">(<\/span>ename<span class=\"token punctuation\">,<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">&#061;<\/span> <span class=\"token string\">&#039;J&#039;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> empno  <span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span> job     <span class=\"token operator\">|<\/span> mgr  <span class=\"token operator\">|<\/span> hiredate            <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> comm <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007566<\/span> <span class=\"token operator\">|<\/span> JONES <span class=\"token operator\">|<\/span> MANAGER <span class=\"token operator\">|<\/span> <span class=\"token number\">7839<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">04<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">02<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007900<\/span> <span class=\"token operator\">|<\/span> JAMES <span class=\"token operator\">|<\/span> CLERK   <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">12<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">03<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">950.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">2<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">1<\/span> warning <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>\u6309\u7167\u90e8\u95e8\u53f7\u5347\u5e8f\u6392\u5e8f&#xff0c;\u5f53\u90e8\u95e8\u53f7\u76f8\u540c\u65f6\u6309\u96c7\u5458\u7684\u5de5\u8d44\u964d\u5e8f\u6392\u5e8f<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> ename<span class=\"token punctuation\">,<\/span> sal<span class=\"token punctuation\">,<\/span> deptno <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">order<\/span> <span class=\"token keyword\">by<\/span> deptno<span class=\"token punctuation\">,<\/span> sal <span class=\"token keyword\">desc<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ename  <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> KING   <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> CLARK  <span class=\"token operator\">|<\/span> <span class=\"token number\">2450.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> MILLER <span class=\"token operator\">|<\/span> <span class=\"token number\">1300.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SCOTT  <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> FORD   <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> JONES  <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> ADAMS  <span class=\"token operator\">|<\/span> <span class=\"token number\">1100.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SMITH  <span class=\"token operator\">|<\/span>  <span class=\"token number\">800.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> BLAKE  <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> ALLEN  <span class=\"token operator\">|<\/span> <span class=\"token number\">1600.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> TURNER <span class=\"token operator\">|<\/span> <span class=\"token number\">1500.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> WARD   <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> MARTIN <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> JAMES  <span class=\"token operator\">|<\/span>  <span class=\"token number\">950.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">14<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>\u4f7f\u7528\u5e74\u85aa\u8fdb\u884c\u964d\u5e8f\u6392\u5e8f<\/li>\n<\/ul>\n<p>\u6ce8\u610f&#xff1a;NULL\u4e0e\u4efb\u610f\u503c\u76f8\u52a0\u90fd\u4e3aNULL<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> ename<span class=\"token punctuation\">,<\/span> sal<span class=\"token punctuation\">,<\/span> comm<span class=\"token punctuation\">,<\/span> sal<span class=\"token operator\">*<\/span><span class=\"token number\">12<\/span><span class=\"token operator\">&#043;<\/span>ifnull<span class=\"token punctuation\">(<\/span>comm<span class=\"token punctuation\">,<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> \u5e74\u85aa <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">order<\/span> <span class=\"token keyword\">by<\/span> sal<span class=\"token operator\">*<\/span><span class=\"token number\">12<\/span><span class=\"token operator\">&#043;<\/span>ifnull<span class=\"token punctuation\">(<\/span>comm<span class=\"token punctuation\">,<\/span><span class=\"token number\">0<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">desc<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ename  <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> comm    <span class=\"token operator\">|<\/span> \u5e74\u85aa     <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> KING   <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">60000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SCOTT  <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">36000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> FORD   <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">36000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> JONES  <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">35700.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> BLAKE  <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">34200.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> CLARK  <span class=\"token operator\">|<\/span> <span class=\"token number\">2450.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">29400.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> ALLEN  <span class=\"token operator\">|<\/span> <span class=\"token number\">1600.00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">300.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">19500.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> TURNER <span class=\"token operator\">|<\/span> <span class=\"token number\">1500.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token number\">0.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">18000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> MARTIN <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1400.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">16400.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> MILLER <span class=\"token operator\">|<\/span> <span class=\"token number\">1300.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">15600.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> WARD   <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">500.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">15500.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> ADAMS  <span class=\"token operator\">|<\/span> <span class=\"token number\">1100.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">13200.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> JAMES  <span class=\"token operator\">|<\/span>  <span class=\"token number\">950.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">11400.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SMITH  <span class=\"token operator\">|<\/span>  <span class=\"token number\">800.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">9600.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token number\">14<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>\u663e\u793a\u5de5\u8d44\u6700\u9ad8\u7684\u5458\u5de5\u7684\u540d\u5b57\u548c\u5de5\u4f5c\u5c97\u4f4d<\/li>\n<\/ul>\n<p>\u4e24\u6761\u8bed\u53e5&#xff1a;<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token function\">max<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">from<\/span> emp<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token function\">max<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>  <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token number\">1<\/span> <span class=\"token keyword\">row<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token operator\">*<\/span> <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> sal <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">5000<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> empno  <span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span> job       <span class=\"token operator\">|<\/span> mgr  <span class=\"token operator\">|<\/span> hiredate            <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> comm <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007839<\/span> <span class=\"token operator\">|<\/span> KING  <span class=\"token operator\">|<\/span> PRESIDENT <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">11<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">17<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">1<\/span> <span class=\"token keyword\">row<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p>\u4e00\u6761\u8bed\u53e5&#xff1a;\u6267\u884c\u65f6&#xff0c;\u5148\u6267\u884c&#xff08;&#xff09;\u5185\u7684\u5b50\u67e5\u8be2<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token operator\">*<\/span> <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> sal <span class=\"token operator\">&#061;<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">select<\/span> <span class=\"token function\">max<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">from<\/span> emp<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> empno  <span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span> job       <span class=\"token operator\">|<\/span> mgr  <span class=\"token operator\">|<\/span> hiredate            <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> comm <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007839<\/span> <span class=\"token operator\">|<\/span> KING  <span class=\"token operator\">|<\/span> PRESIDENT <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">11<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">17<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">1<\/span> <span class=\"token keyword\">row<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>\u663e\u793a\u5de5\u8d44\u9ad8\u4e8e\u5e73\u5747\u5de5\u8d44\u7684\u5458\u5de5\u4fe1\u606f<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span>  <span class=\"token keyword\">select<\/span> <span class=\"token operator\">*<\/span> <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> sal <span class=\"token operator\">&gt;<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">select<\/span> <span class=\"token function\">avg<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">from<\/span> emp<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> empno  <span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span> job       <span class=\"token operator\">|<\/span> mgr  <span class=\"token operator\">|<\/span> hiredate            <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> comm <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007566<\/span> <span class=\"token operator\">|<\/span> JONES <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span> <span class=\"token number\">7839<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">04<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">02<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007698<\/span> <span class=\"token operator\">|<\/span> BLAKE <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span> <span class=\"token number\">7839<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">05<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">01<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007782<\/span> <span class=\"token operator\">|<\/span> CLARK <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span> <span class=\"token number\">7839<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">06<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">09<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2450.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007788<\/span> <span class=\"token operator\">|<\/span> SCOTT <span class=\"token operator\">|<\/span> ANALYST   <span class=\"token operator\">|<\/span> <span class=\"token number\">7566<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1987<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">04<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">19<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007839<\/span> <span class=\"token operator\">|<\/span> KING  <span class=\"token operator\">|<\/span> PRESIDENT <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">11<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">17<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007902<\/span> <span class=\"token operator\">|<\/span> FORD  <span class=\"token operator\">|<\/span> ANALYST   <span class=\"token operator\">|<\/span> <span class=\"token number\">7566<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">12<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">03<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">6<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>\u663e\u793a\u6bcf\u4e2a\u90e8\u95e8\u7684\u5e73\u5747\u5de5\u8d44\u548c\u6700\u9ad8\u5de5\u8d44<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> deptno<span class=\"token punctuation\">,<\/span> <span class=\"token function\">avg<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span> \u5e73\u5747\u5de5\u8d44<span class=\"token punctuation\">,<\/span> <span class=\"token function\">max<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span> \u6700\u9ad8\u5de5\u8d44 <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> deptno<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> \u5e73\u5747\u5de5\u8d44     <span class=\"token operator\">|<\/span> \u6700\u9ad8\u5de5\u8d44     <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">2175.000000<\/span> <span class=\"token operator\">|<\/span>      <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">1566.666667<\/span> <span class=\"token operator\">|<\/span>      <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">2916.666667<\/span> <span class=\"token operator\">|<\/span>      <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">3<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p>\u66f4\u7f8e\u89c2\u4e00\u4e9b&#xff1a;<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> deptno<span class=\"token punctuation\">,<\/span> <span class=\"token function\">format<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">avg<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">)<\/span> \u5e73\u5747\u5de5\u8d44<span class=\"token punctuation\">,<\/span> <span class=\"token function\">max<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span> \u6700\u9ad8\u5de5\u8d44 <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> deptno<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> \u5e73\u5747\u5de5\u8d44     <span class=\"token operator\">|<\/span> \u6700\u9ad8\u5de5\u8d44     <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">175.00<\/span>     <span class=\"token operator\">|<\/span>      <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">566.67<\/span>     <span class=\"token operator\">|<\/span>      <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">916.67<\/span>     <span class=\"token operator\">|<\/span>      <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">3<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>\u663e\u793a\u5e73\u5747\u5de5\u8d44\u4f4e\u4e8e2000\u7684\u90e8\u95e8\u53f7\u548c\u5b83\u7684\u5e73\u5747\u5de5\u8d44<\/li>\n<\/ul>\n<p> mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> deptno<span class=\"token punctuation\">,<\/span> <span class=\"token function\">avg<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span> \u5e73\u5747\u5de5\u8d44 <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> deptno <span class=\"token keyword\">having<\/span> \u5e73\u5747\u5de5\u8d44 <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">2000<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> \u5e73\u5747\u5de5\u8d44     <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">1566.666667<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">1<\/span> <span class=\"token keyword\">row<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p>\u4e3a\u4ec0\u4e48\u683c\u5f0f\u5316\u4e86\u4e4b\u540e\u4e0d\u5bf9\u5462&#xff1f;<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> deptno<span class=\"token punctuation\">,<\/span> <span class=\"token function\">format<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">avg<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">)<\/span> \u5e73\u5747\u5de5\u8d44 <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> deptno <span class=\"token keyword\">having<\/span> \u5e73\u5747\u5de5\u8d44 <span class=\"token operator\">&lt;<\/span> <span class=\"token number\">2000<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> \u5e73\u5747\u5de5\u8d44     <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">175.00<\/span>     <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">566.67<\/span>     <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">916.67<\/span>     <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">3<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">3<\/span> <span class=\"token keyword\">warnings<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p>\u56e0\u4e3a&#xff1a;\u7531\u4e8e\u4f7f\u7528\u4e86FORMAT\u51fd\u6570&#xff0c;\u5e73\u5747\u5de5\u8d44\u88ab\u683c\u5f0f\u5316\u4e3a\u5e26\u6709\u9017\u53f7\u7684\u5b57\u7b26\u4e32&#xff08;\u4f8b\u59822,175.00&#xff09;\u3002\u5728HAVING\u5b50\u53e5\u4e2d&#xff0c;\u5c06\u8fd9\u4e2a\u5b57\u7b26\u4e32\u4e0e\u6570\u5b572000\u6bd4\u8f83\u65f6&#xff0c;MySQL\u4f1a\u5c1d\u8bd5\u5c06\u5b57\u7b26\u4e32\u8f6c\u6362\u4e3a\u6570\u5b57\u3002\u4f46\u662f&#xff0c;\u7531\u4e8e\u5b57\u7b26\u4e32\u4e2d\u5305\u542b\u9017\u53f7&#xff0c;\u8f6c\u6362\u53ef\u80fd\u4f1a\u5931\u8d25&#xff0c;\u5b9e\u9645\u4e0aMySQL\u4f1a\u622a\u53d6\u5b57\u7b26\u4e32\u4e2d\u76f4\u5230\u7b2c\u4e00\u4e2a\u975e\u6570\u5b57\u5b57\u7b26&#xff08;\u9017\u53f7&#xff09;\u4e4b\u524d\u7684\u6570\u5b57\u90e8\u5206&#xff0c;\u6240\u4ee5&#034;2,175.00&#034;\u4f1a\u88ab\u8f6c\u6362\u4e3a2&#xff0c;\u56e0\u6b64\u6761\u4ef6\u201c\u5e73\u5747\u5de5\u8d44 &lt; 2000\u201d\u5bf9\u4e8e\u6240\u6709\u884c\u90fd\u6210\u7acb<\/p>\n<ul>\n<li>\u663e\u793a\u6bcf\u79cd\u5c97\u4f4d\u7684\u96c7\u5458\u603b\u6570&#xff0c;\u5e73\u5747\u5de5\u8d44<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> job<span class=\"token punctuation\">,<\/span> <span class=\"token function\">format<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">avg<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token function\">count<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span> \u5458\u5de5\u4eba\u6570 <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> job<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> job       <span class=\"token operator\">|<\/span> <span class=\"token function\">format<\/span><span class=\"token punctuation\">(<\/span><span class=\"token function\">avg<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">|<\/span> \u5458\u5de5\u4eba\u6570     <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> CLERK     <span class=\"token operator\">|<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">037.50<\/span>            <span class=\"token operator\">|<\/span>            <span class=\"token number\">4<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SALESMAN  <span class=\"token operator\">|<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">400.00<\/span>            <span class=\"token operator\">|<\/span>            <span class=\"token number\">4<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">758.33<\/span>            <span class=\"token operator\">|<\/span>            <span class=\"token number\">3<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> ANALYST   <span class=\"token operator\">|<\/span> <span class=\"token number\">3<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">000.00<\/span>            <span class=\"token operator\">|<\/span>            <span class=\"token number\">2<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> PRESIDENT <span class=\"token operator\">|<\/span> <span class=\"token number\">5<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">000.00<\/span>            <span class=\"token operator\">|<\/span>            <span class=\"token number\">1<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">5<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<h2>\u4e8c\u3001\u591a\u8868\u67e5\u8be2<\/h2>\n<p>\u5f53\u6570\u636e\u6765\u81ea\u4e0d\u540c\u7684\u8868\u65f6&#xff0c;\u6211\u4eec\u9700\u8981\u7528\u5230\u591a\u8868\u67e5\u8be2<\/p>\n<ul>\n<li>\u663e\u793a\u96c7\u5458\u540d\u3001\u96c7\u5458\u5de5\u8d44\u4ee5\u53ca\u6240\u5728\u90e8\u95e8\u7684\u540d\u5b57<\/li>\n<\/ul>\n<p>\u56e0\u4e3a\u4e0a\u9762\u7684\u6570\u636e\u6765\u81eaEMP\u548cDEPT\u8868&#xff0c;\u56e0\u6b64\u8981\u591a\u8868\u67e5\u8be2<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token operator\">*<\/span> <span class=\"token keyword\">from<\/span> emp<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> empno  <span class=\"token operator\">|<\/span> ename  <span class=\"token operator\">|<\/span> job       <span class=\"token operator\">|<\/span> mgr  <span class=\"token operator\">|<\/span> hiredate            <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> comm    <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007369<\/span> <span class=\"token operator\">|<\/span> SMITH  <span class=\"token operator\">|<\/span> CLERK     <span class=\"token operator\">|<\/span> <span class=\"token number\">7902<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1980<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">12<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">17<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">800.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007499<\/span> <span class=\"token operator\">|<\/span> ALLEN  <span class=\"token operator\">|<\/span> SALESMAN  <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">02<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">20<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1600.00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">300.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007521<\/span> <span class=\"token operator\">|<\/span> WARD   <span class=\"token operator\">|<\/span> SALESMAN  <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">02<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">22<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">500.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007566<\/span> <span class=\"token operator\">|<\/span> JONES  <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span> <span class=\"token number\">7839<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">04<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">02<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007654<\/span> <span class=\"token operator\">|<\/span> MARTIN <span class=\"token operator\">|<\/span> SALESMAN  <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">09<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">28<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1400.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007698<\/span> <span class=\"token operator\">|<\/span> BLAKE  <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span> <span class=\"token number\">7839<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">05<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">01<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007782<\/span> <span class=\"token operator\">|<\/span> CLARK  <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span> <span class=\"token number\">7839<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">06<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">09<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2450.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007788<\/span> <span class=\"token operator\">|<\/span> SCOTT  <span class=\"token operator\">|<\/span> ANALYST   <span class=\"token operator\">|<\/span> <span class=\"token number\">7566<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1987<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">04<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">19<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007839<\/span> <span class=\"token operator\">|<\/span> KING   <span class=\"token operator\">|<\/span> PRESIDENT <span class=\"token operator\">|<\/span> <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">11<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">17<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007844<\/span> <span class=\"token operator\">|<\/span> TURNER <span class=\"token operator\">|<\/span> SALESMAN  <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">09<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">08<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1500.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token number\">0.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007876<\/span> <span class=\"token operator\">|<\/span> ADAMS  <span class=\"token operator\">|<\/span> CLERK     <span class=\"token operator\">|<\/span> <span class=\"token number\">7788<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1987<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">05<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">23<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1100.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007900<\/span> <span class=\"token operator\">|<\/span> JAMES  <span class=\"token operator\">|<\/span> CLERK     <span class=\"token operator\">|<\/span> <span class=\"token number\">7698<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">12<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">03<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span>  <span class=\"token number\">950.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007902<\/span> <span class=\"token operator\">|<\/span> FORD   <span class=\"token operator\">|<\/span> ANALYST   <span class=\"token operator\">|<\/span> <span class=\"token number\">7566<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1981<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">12<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">03<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007934<\/span> <span class=\"token operator\">|<\/span> MILLER <span class=\"token operator\">|<\/span> CLERK     <span class=\"token operator\">|<\/span> <span class=\"token number\">7782<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1982<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">01<\/span><span class=\"token operator\">&#8211;<\/span><span class=\"token number\">23<\/span> <span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span>:<span class=\"token number\">00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1300.00<\/span> <span class=\"token operator\">|<\/span>    <span class=\"token boolean\">NULL<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">14<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.01<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token operator\">*<\/span> <span class=\"token keyword\">from<\/span> dept<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> dname      <span class=\"token operator\">|<\/span> loc      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">40<\/span> <span class=\"token operator\">|<\/span> OPERATIONS <span class=\"token operator\">|<\/span> BOSTON   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token number\">4<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260115145714-6969004a361c6.png\" alt=\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\" \/><\/p>\n<p>\u591a\u8868\u67e5\u8be2\u7684\u672c\u8d28\u662f\u4e24\u4e2a\u8868\u4e4b\u95f4\u5c06\u6570\u636e\u8fdb\u884c\u7a77\u4e3e\u7ec4\u5408\u5373\u7b1b\u5361\u5c14\u79ef&#xff0c;\u5373emp\u8868\u4e2d\u7684\u7b2c\u4e00\u6761\u4fe1\u606f\u5206\u522b\u4e0edept\u8868\u4e2d\u7684\u6bcf\u4e00\u6761\u4fe1\u606f\u8fdb\u884c\u6574\u5408&#xff0c;\u7136\u540eemp\u8868\u4e2d\u7b2c\u4e8c\u6761\u4fe1\u606f\u5206\u522b\u4e0edept\u8868\u4e2d\u7684\u6bcf\u4e00\u6761\u4fe1\u606f\u8fdb\u884c\u6574\u5408\u2026\u4ee5\u6b64\u7c7b\u63a8<\/p>\n<p>\u6ce8\u610f: \u7b1b\u5361\u5c14\u79ef\u4e4b\u540e\u7684\u7ed3\u679c\u6709\u4e00\u4e9b\u6570\u636e\u662f\u65e0\u6548\u7684&#xff0c;\u56e0\u6b64\u6211\u4eec\u9700\u8981\u52a0\u4e0a\u8fc7\u6ee4\u6761\u4ef6<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260115145714-6969004aeeb92.png\" alt=\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\" \/><\/p>\n<ul>\n<li>\u663e\u793a\u90e8\u95e8\u53f7\u4e3a10\u7684\u90e8\u95e8\u540d&#xff0c;\u5458\u5de5\u540d\u548c\u5de5\u8d44<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> emp<span class=\"token punctuation\">.<\/span>deptno<span class=\"token punctuation\">,<\/span> ename<span class=\"token punctuation\">,<\/span> sal<span class=\"token punctuation\">,<\/span> dname <span class=\"token keyword\">from<\/span> emp<span class=\"token punctuation\">,<\/span> dept <span class=\"token keyword\">where<\/span> emp<span class=\"token punctuation\">.<\/span>deptno <span class=\"token operator\">&#061;<\/span> dept<span class=\"token punctuation\">.<\/span>deptno <span class=\"token operator\">&amp;&amp;<\/span> emp<span class=\"token punctuation\">.<\/span>deptno <span class=\"token operator\">&#061;<\/span> <span class=\"token number\">10<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> ename  <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> dname      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> CLARK  <span class=\"token operator\">|<\/span> <span class=\"token number\">2450.00<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> KING   <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> MILLER <span class=\"token operator\">|<\/span> <span class=\"token number\">1300.00<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#043;<\/span><br \/>\n<span class=\"token number\">3<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span><span class=\"token punctuation\">,<\/span> <span class=\"token number\">1<\/span> warning <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>\u663e\u793a\u5404\u4e2a\u5458\u5de5\u7684\u59d3\u540d&#xff0c;\u5de5\u8d44&#xff0c;\u53ca\u5de5\u8d44\u7ea7\u522b<\/li>\n<\/ul>\n<p>\u9700\u8981\u5c06emp\u8868\u4e0esalgrade\u8868\u7ed3\u5408<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> ename<span class=\"token punctuation\">,<\/span> sal<span class=\"token punctuation\">,<\/span> grade <span class=\"token keyword\">from<\/span> emp<span class=\"token punctuation\">,<\/span> salgrade <span class=\"token keyword\">where<\/span> emp<span class=\"token punctuation\">.<\/span>sal <span class=\"token operator\">between<\/span> losal <span class=\"token operator\">and<\/span>  hisal<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ename  <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> grade <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> SMITH  <span class=\"token operator\">|<\/span>  <span class=\"token number\">800.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">1<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> ALLEN  <span class=\"token operator\">|<\/span> <span class=\"token number\">1600.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">3<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> WARD   <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">2<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> JONES  <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">4<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> MARTIN <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">2<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> BLAKE  <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">4<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> CLARK  <span class=\"token operator\">|<\/span> <span class=\"token number\">2450.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">4<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SCOTT  <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">4<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> KING   <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">5<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> TURNER <span class=\"token operator\">|<\/span> <span class=\"token number\">1500.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">3<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> ADAMS  <span class=\"token operator\">|<\/span> <span class=\"token number\">1100.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">1<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> JAMES  <span class=\"token operator\">|<\/span>  <span class=\"token number\">950.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">1<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> FORD   <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">4<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> MILLER <span class=\"token operator\">|<\/span> <span class=\"token number\">1300.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">2<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token number\">14<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<h2>\u4e09\u3001\u81ea\u8fde\u63a5<\/h2>\n<p>\u81ea\u8fde\u63a5\u662f\u5c06\u540c\u4e00\u5f20\u8868\u505a\u7b1b\u5361\u5c14\u79ef&#xff0c;\u6b64\u65f6\u81f3\u5c11\u7ed9\u4e00\u5f20\u8868\u8d77\u522b\u540d<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token operator\">*<\/span> <span class=\"token keyword\">from<\/span> dept<span class=\"token punctuation\">,<\/span> dept<span class=\"token punctuation\">;<\/span><br \/>\nERROR <span class=\"token number\">1066<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">42000<\/span><span class=\"token punctuation\">)<\/span>: <span class=\"token operator\">Not<\/span> <span class=\"token keyword\">unique<\/span> <span class=\"token keyword\">table<\/span><span class=\"token operator\">\/<\/span>alias: <span class=\"token string\">&#039;dept&#039;<\/span><br \/>\nmysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token operator\">*<\/span> <span class=\"token keyword\">from<\/span> dept d1<span class=\"token punctuation\">,<\/span> dept<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> dname      <span class=\"token operator\">|<\/span> loc      <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> dname      <span class=\"token operator\">|<\/span> loc      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">40<\/span> <span class=\"token operator\">|<\/span> OPERATIONS <span class=\"token operator\">|<\/span> BOSTON   <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">40<\/span> <span class=\"token operator\">|<\/span> OPERATIONS <span class=\"token operator\">|<\/span> BOSTON   <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">40<\/span> <span class=\"token operator\">|<\/span> OPERATIONS <span class=\"token operator\">|<\/span> BOSTON   <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">40<\/span> <span class=\"token operator\">|<\/span> OPERATIONS <span class=\"token operator\">|<\/span> BOSTON   <span class=\"token operator\">|<\/span>     <span class=\"token number\">40<\/span> <span class=\"token operator\">|<\/span> OPERATIONS <span class=\"token operator\">|<\/span> BOSTON   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span>     <span class=\"token number\">40<\/span> <span class=\"token operator\">|<\/span> OPERATIONS <span class=\"token operator\">|<\/span> BOSTON   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span>     <span class=\"token number\">40<\/span> <span class=\"token operator\">|<\/span> OPERATIONS <span class=\"token operator\">|<\/span> BOSTON   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span>     <span class=\"token number\">40<\/span> <span class=\"token operator\">|<\/span> OPERATIONS <span class=\"token operator\">|<\/span> BOSTON   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token number\">16<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>\u663e\u793a\u5458\u5de5FORD\u7684\u4e0a\u7ea7\u9886\u5bfc\u7684\u7f16\u53f7\u548c\u59d3\u540d&#xff08;mgr\u662f\u5458\u5de5\u9886\u5bfc\u7684\u7f16\u53f7&#xff09;<\/li>\n<\/ul>\n<p>\u4f7f\u7528\u5b50\u67e5\u8be2&#xff1a;<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> empno<span class=\"token punctuation\">,<\/span> ename <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> emp<span class=\"token punctuation\">.<\/span>empno<span class=\"token operator\">&#061;<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">select<\/span> mgr <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> ename<span class=\"token operator\">&#061;<\/span><span class=\"token string\">&#039;FORD &#039;<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> empno  <span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007566<\/span> <span class=\"token operator\">|<\/span> JONES <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token number\">1<\/span> <span class=\"token keyword\">row<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p>\u4f7f\u7528\u81ea\u8fde\u63a5&#xff1a;<\/p>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> leader<span class=\"token punctuation\">.<\/span>empno <span class=\"token punctuation\">,<\/span>leader<span class=\"token punctuation\">.<\/span>ename <span class=\"token keyword\">from<\/span> emp leader<span class=\"token punctuation\">,<\/span> emp worker <span class=\"token keyword\">where<\/span> leader<span class=\"token punctuation\">.<\/span>empno <span class=\"token operator\">&#061;<\/span> worker<span class=\"token punctuation\">.<\/span>mgr <span class=\"token operator\">and<\/span> worker<span class=\"token punctuation\">.<\/span>ename<span class=\"token operator\">&#061;<\/span><span class=\"token string\">&#039;FORD &#039;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> empno  <span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token number\">007566<\/span> <span class=\"token operator\">|<\/span> JONES <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token number\">1<\/span> <span class=\"token keyword\">row<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<h2>\u56db\u3001\u5b50\u67e5\u8be2<\/h2>\n<p>\u5b50\u67e5\u8be2\u662f\u6307\u5d4c\u5165\u5728\u5176\u4ed6sql\u8bed\u53e5\u4e2d\u7684select\u8bed\u53e5&#xff0c;\u4e5f\u53eb\u5d4c\u5957\u67e5\u8be2<\/p>\n<h3>1.\u5355\u884c\u5b50\u67e5\u8be2<\/h3>\n<ul>\n<li>\u663e\u793aSMITH\u540c\u4e00\u90e8\u95e8\u7684\u5458\u5de5<\/li>\n<\/ul>\n<h3>2.\u591a\u884c\u5b50\u67e5\u8be2<\/h3>\n<p>\u8fd4\u56de\u591a\u884c\u8bb0\u5f55\u7684\u5b50\u67e5\u8be2<\/p>\n<ul>\n<li>in\u5173\u952e\u5b57&#xff1b;\u67e5\u8be2\u548c10\u53f7\u90e8\u95e8\u7684\u5de5\u4f5c\u5c97\u4f4d\u76f8\u540c\u7684\u96c7\u5458\u7684\u540d\u5b57&#xff0c;\u5c97\u4f4d&#xff0c;\u5de5\u8d44&#xff0c;\u90e8\u95e8\u53f7&#xff0c;\u4f46\u662f\u4e0d\u5305\u542b10\u81ea\u5df1\u7684<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> ename<span class=\"token punctuation\">,<\/span> job<span class=\"token punctuation\">,<\/span> sal<span class=\"token punctuation\">,<\/span> deptno <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> job <span class=\"token operator\">in<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">select<\/span> <span class=\"token keyword\">distinct<\/span> job <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> deptno<span class=\"token operator\">&#061;<\/span><span class=\"token number\">10<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">and<\/span> deptno<span class=\"token operator\">&lt;&gt;<\/span><span class=\"token number\">10<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span> job     <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> SMITH <span class=\"token operator\">|<\/span> CLERK   <span class=\"token operator\">|<\/span>  <span class=\"token number\">800.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> JONES <span class=\"token operator\">|<\/span> MANAGER <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> BLAKE <span class=\"token operator\">|<\/span> MANAGER <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> ADAMS <span class=\"token operator\">|<\/span> CLERK   <span class=\"token operator\">|<\/span> <span class=\"token number\">1100.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> JAMES <span class=\"token operator\">|<\/span> CLERK   <span class=\"token operator\">|<\/span>  <span class=\"token number\">950.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">5<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>all\u5173\u952e\u5b57&#xff1b;\u663e\u793a\u5de5\u8d44\u6bd4\u90e8\u95e830\u7684\u6240\u6709\u5458\u5de5\u7684\u5de5\u8d44\u9ad8\u7684\u5458\u5de5\u7684\u59d3\u540d\u3001\u5de5\u8d44\u548c\u90e8\u95e8\u53f7 \u5373\u6bd4\u90e8\u95e830\u7684\u6700\u9ad8\u5de5\u8d44\u8fd8\u9ad8\u7684<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> ename<span class=\"token punctuation\">,<\/span> sal<span class=\"token punctuation\">,<\/span> deptno <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> sal <span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">all<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">select<\/span> sal <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> deptno<span class=\"token operator\">&#061;<\/span><span class=\"token number\">30<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> JONES <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SCOTT <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> KING  <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> FORD  <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">4<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>any\u5173\u952e\u5b57&#xff1b;\u663e\u793a\u5de5\u8d44\u6bd4\u90e8\u95e830\u7684\u4efb\u610f\u5458\u5de5\u7684\u5de5\u8d44\u9ad8\u7684\u5458\u5de5\u7684\u59d3\u540d\u3001\u5de5\u8d44\u548c\u90e8\u95e8\u53f7&#xff08;\u5305\u542b\u81ea\u5df1\u90e8\u95e8\u7684\u5458\u5de5&#xff09; \u5373\u6bd4\u90e8\u95e830\u7684\u6700\u4f4e\u5de5\u8d44\u9ad8\u7684<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> ename<span class=\"token punctuation\">,<\/span> sal<span class=\"token punctuation\">,<\/span> deptno <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> sal <span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">any<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">select<\/span> sal <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> deptno<span class=\"token operator\">&#061;<\/span><span class=\"token number\">30<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ename  <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ALLEN  <span class=\"token operator\">|<\/span> <span class=\"token number\">1600.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> WARD   <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> JONES  <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> MARTIN <span class=\"token operator\">|<\/span> <span class=\"token number\">1250.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> BLAKE  <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> CLARK  <span class=\"token operator\">|<\/span> <span class=\"token number\">2450.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SCOTT  <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> KING   <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> TURNER <span class=\"token operator\">|<\/span> <span class=\"token number\">1500.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> ADAMS  <span class=\"token operator\">|<\/span> <span class=\"token number\">1100.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> FORD   <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> MILLER <span class=\"token operator\">|<\/span> <span class=\"token number\">1300.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">12<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<h3>3.\u591a\u5217\u5b50\u67e5\u8be2<\/h3>\n<li>\u5355\u884c\u5b50\u67e5\u8be2\u662f\u6307\u5b50\u67e5\u8be2\u53ea\u8fd4\u56de\u5355\u5217&#xff0c;\u5355\u884c\u6570\u636e&#xff1b;<\/li>\n<li>\u591a\u884c\u5b50\u67e5\u8be2\u662f\u6307\u8fd4\u56de\u5355\u5217\u591a\u884c\u6570\u636e&#xff0c;\u90fd\u662f\u9488\u5bf9\u5355\u5217\u800c\u8a00\u7684;<\/li>\n<li>\u591a\u5217\u5b50\u67e5\u8be2\u662f\u6307\u67e5\u8be2\u8fd4\u56de\u591a\u4e2a\u5217\u6570\u636e\u7684\u5b50\u67e5\u8be2\u8bed\u53e5;<\/li>\n<ul>\n<li>\u67e5\u8be2\u548cSMITH\u7684\u90e8\u95e8\u548c\u5c97\u4f4d\u5b8c\u5168\u76f8\u540c\u7684\u6240\u6709\u96c7\u5458&#xff0c;\u4e0d\u542bSMITH\u672c\u4eba<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> ename <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> <span class=\"token punctuation\">(<\/span>deptno<span class=\"token punctuation\">,<\/span> job<span class=\"token punctuation\">)<\/span><span class=\"token operator\">&#061;<\/span><span class=\"token punctuation\">(<\/span><span class=\"token keyword\">select<\/span> deptno<span class=\"token punctuation\">,<\/span> job <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> ename<span class=\"token operator\">&#061;<\/span><span class=\"token string\">&#039;SMITH&#039;<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">and<\/span> ename <span class=\"token operator\">&lt;&gt;<\/span> <span class=\"token string\">&#039;SMITH&#039;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ADAMS <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token number\">1<\/span> <span class=\"token keyword\">row<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<h3>4.\u5728from\u5b50\u53e5\u4e2d\u4f7f\u7528\u5b50\u67e5\u8be2<\/h3>\n<p>\u5b50\u67e5\u8be2\u8bed\u53e5\u51fa\u73b0\u5728from\u5b50\u53e5\u4e2d\u3002\u8fd9\u91cc\u8981\u7528\u5230\u6570\u636e\u67e5\u8be2\u7684\u6280\u5de7&#xff0c;\u628a\u4e00\u4e2a\u5b50\u67e5\u8be2\u5f53\u505a\u4e00\u4e2a\u4e34\u65f6\u8868\u4f7f\u7528\u3002<\/p>\n<ul>\n<li>\u663e\u793a\u6bcf\u4e2a\u9ad8\u4e8e\u81ea\u5df1\u90e8\u95e8\u5e73\u5747\u5de5\u8d44\u7684\u5458\u5de5\u7684\u59d3\u540d\u3001\u90e8\u95e8\u3001\u5de5\u8d44\u3001\u5e73\u5747\u5de5\u8d44<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> ename<span class=\"token punctuation\">,<\/span> deptno<span class=\"token punctuation\">,<\/span> sal<span class=\"token punctuation\">,<\/span> <span class=\"token function\">format<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">,<\/span><span class=\"token number\">2<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">from<\/span> emp<span class=\"token punctuation\">,<\/span><br \/>\n    <span class=\"token operator\">&#8211;<\/span><span class=\"token operator\">&gt;<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">select<\/span> <span class=\"token function\">avg<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span> asal<span class=\"token punctuation\">,<\/span> deptno dt <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> deptno<span class=\"token punctuation\">)<\/span> tmp<br \/>\n    <span class=\"token operator\">&#8211;<\/span><span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">where<\/span> emp<span class=\"token punctuation\">.<\/span>sal <span class=\"token operator\">&gt;<\/span> tmp<span class=\"token punctuation\">.<\/span>asal <span class=\"token operator\">and<\/span> emp<span class=\"token punctuation\">.<\/span>deptno<span class=\"token operator\">&#061;<\/span>tmp<span class=\"token punctuation\">.<\/span>dt<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> <span class=\"token function\">format<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">,<\/span><span class=\"token number\">2<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> FORD  <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">000.00<\/span>      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SCOTT <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">000.00<\/span>      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> JONES <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">975.00<\/span>      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> BLAKE <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">850.00<\/span>      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> ALLEN <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1600.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">1<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">600.00<\/span>      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> KING  <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">5<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">000.00<\/span>      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8212;&#8212;&#043;<\/span><br \/>\n<span class=\"token number\">6<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>\u67e5\u627e\u6bcf\u4e2a\u90e8\u95e8\u5de5\u8d44\u6700\u9ad8\u7684\u4eba\u7684\u59d3\u540d\u3001\u5de5\u8d44\u3001\u90e8\u95e8\u3001\u6700\u9ad8\u5de5\u8d44<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> emp<span class=\"token punctuation\">.<\/span>ename<span class=\"token punctuation\">,<\/span> emp<span class=\"token punctuation\">.<\/span>sal<span class=\"token punctuation\">,<\/span> emp<span class=\"token punctuation\">.<\/span>deptno<span class=\"token punctuation\">,<\/span> ms <span class=\"token keyword\">from<\/span> emp<span class=\"token punctuation\">,<\/span><br \/>\n    <span class=\"token operator\">&#8211;<\/span><span class=\"token operator\">&gt;<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">select<\/span> <span class=\"token function\">max<\/span><span class=\"token punctuation\">(<\/span>sal<span class=\"token punctuation\">)<\/span> ms<span class=\"token punctuation\">,<\/span> deptno <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> deptno<span class=\"token punctuation\">)<\/span> tmp<br \/>\n    <span class=\"token operator\">&#8211;<\/span><span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">where<\/span> emp<span class=\"token punctuation\">.<\/span>deptno<span class=\"token operator\">&#061;<\/span>tmp<span class=\"token punctuation\">.<\/span>deptno <span class=\"token operator\">and<\/span> emp<span class=\"token punctuation\">.<\/span>sal<span class=\"token operator\">&#061;<\/span>tmp<span class=\"token punctuation\">.<\/span>ms<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> ms      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> BLAKE <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SCOTT <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> KING  <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> FORD  <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#043;<\/span><br \/>\n<span class=\"token number\">4<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>\u663e\u793a\u6bcf\u4e2a\u90e8\u95e8\u7684\u4fe1\u606f&#xff08;\u90e8\u95e8\u540d&#xff0c;\u7f16\u53f7&#xff0c;\u5730\u5740&#xff09;\u548c\u4eba\u5458\u6570\u91cf \u4f7f\u7528\u591a\u8868&#xff1a;<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> dept<span class=\"token punctuation\">.<\/span>dname<span class=\"token punctuation\">,<\/span> dept<span class=\"token punctuation\">.<\/span>deptno<span class=\"token punctuation\">,<\/span> dept<span class=\"token punctuation\">.<\/span>loc<span class=\"token punctuation\">,<\/span> <span class=\"token function\">count<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span> \u90e8\u95e8\u4eba\u6570 <span class=\"token keyword\">from<\/span> emp<span class=\"token punctuation\">,<\/span> dept<br \/>\n    <span class=\"token operator\">&#8211;<\/span><span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">where<\/span> emp<span class=\"token punctuation\">.<\/span>deptno<span class=\"token operator\">&#061;<\/span>dept<span class=\"token punctuation\">.<\/span>deptno <span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> dept<span class=\"token punctuation\">.<\/span>deptno<span class=\"token punctuation\">,<\/span> dept<span class=\"token punctuation\">.<\/span>dname<span class=\"token punctuation\">,<\/span> dept<span class=\"token punctuation\">.<\/span>loc<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> dname      <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> loc      <span class=\"token operator\">|<\/span> \u90e8\u95e8\u4eba\u6570     <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span>            <span class=\"token number\">5<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span>            <span class=\"token number\">6<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span>            <span class=\"token number\">3<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">3<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p>\u4f7f\u7528\u5b50\u67e5\u8be2&#xff1a;<\/p>\n<p><span class=\"token comment\">#1.\u5bf9emp\u8868\u8fdb\u884c\u4eba\u5458\u7edf\u8ba1<\/span><br \/>\nmysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> <span class=\"token function\">count<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span> deptno <span class=\"token keyword\">from<\/span>  emp <span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> deptno <span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;-&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> <span class=\"token function\">count<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;-&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>        <span class=\"token number\">5<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>        <span class=\"token number\">6<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>        <span class=\"token number\">3<\/span> <span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8212;-&#043;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">3<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<p><span class=\"token comment\">#2.\u5c06\u4e0a\u9762\u7684\u8868\u770b\u4f5c\u4e34\u65f6\u8868<\/span><br \/>\nmysql<span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">select<\/span> dept<span class=\"token punctuation\">.<\/span>deptno<span class=\"token punctuation\">,<\/span> dname<span class=\"token punctuation\">,<\/span> mycnt<span class=\"token punctuation\">,<\/span> loc <span class=\"token keyword\">from<\/span> dept<span class=\"token punctuation\">,<\/span><br \/>\n    <span class=\"token operator\">&#8211;<\/span><span class=\"token operator\">&gt;<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token keyword\">select<\/span> <span class=\"token function\">count<\/span><span class=\"token punctuation\">(<\/span><span class=\"token operator\">*<\/span><span class=\"token punctuation\">)<\/span> mycnt<span class=\"token punctuation\">,<\/span> deptno <span class=\"token keyword\">from<\/span>  emp <span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> deptno<span class=\"token punctuation\">)<\/span> tmp<br \/>\n    <span class=\"token operator\">&#8211;<\/span><span class=\"token operator\">&gt;<\/span> <span class=\"token keyword\">where<\/span> dept<span class=\"token punctuation\">.<\/span>deptno<span class=\"token operator\">&#061;<\/span>tmp<span class=\"token punctuation\">.<\/span>deptno<span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> deptno <span class=\"token operator\">|<\/span> dname      <span class=\"token operator\">|<\/span> mycnt <span class=\"token operator\">|<\/span> loc      <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">10<\/span> <span class=\"token operator\">|<\/span> ACCOUNTING <span class=\"token operator\">|<\/span>     <span class=\"token number\">3<\/span> <span class=\"token operator\">|<\/span> NEW YORK <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">20<\/span> <span class=\"token operator\">|<\/span> RESEARCH   <span class=\"token operator\">|<\/span>     <span class=\"token number\">5<\/span> <span class=\"token operator\">|<\/span> DALLAS   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span>     <span class=\"token number\">30<\/span> <span class=\"token operator\">|<\/span> SALES      <span class=\"token operator\">|<\/span>     <span class=\"token number\">6<\/span> <span class=\"token operator\">|<\/span> CHICAGO  <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;&#8211;&#043;&#8212;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;-&#043;<\/span><br \/>\n<span class=\"token number\">3<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<h2>\u4e94\u3001\u5408\u5e76\u67e5\u8be2<\/h2>\n<p>\u4e3a\u4e86\u5408\u5e76\u591a\u4e2aselect\u7684\u6267\u884c\u7ed3\u679c&#xff0c;\u53ef\u4ee5\u4f7f\u7528\u96c6\u5408\u64cd\u4f5c\u7b26union&#xff0c;union all<\/p>\n<ul>\n<li>union\u64cd\u4f5c\u7b26; \u5c06\u5de5\u8d44\u5927\u4e8e2500\u6216\u804c\u4f4d\u662fMANAGER\u7684\u4eba\u627e\u51fa\u6765 \u8be5\u64cd\u4f5c\u7b26\u7528\u4e8e\u53d6\u5f97\u4e24\u4e2a\u7ed3\u679c\u96c6\u7684\u5e76\u96c6\u3002\u5f53\u4f7f\u7528\u8be5\u64cd\u4f5c\u7b26\u65f6&#xff0c;\u4f1a\u81ea\u52a8\u53bb\u6389\u7ed3\u679c\u96c6\u4e2d\u7684\u91cd\u590d\u884c<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span>  <span class=\"token keyword\">select<\/span> ename <span class=\"token punctuation\">,<\/span> sal <span class=\"token punctuation\">,<\/span> job <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> sal<span class=\"token operator\">&gt;<\/span><span class=\"token number\">2500<\/span> <span class=\"token keyword\">union<\/span><br \/>\n    <span class=\"token operator\">&#8211;<\/span><span class=\"token operator\">&gt;<\/span>  <span class=\"token keyword\">select<\/span> ename <span class=\"token punctuation\">,<\/span> sal <span class=\"token punctuation\">,<\/span> job <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> job<span class=\"token operator\">&#061;<\/span><span class=\"token string\">&#039;MANAGER&#039;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> job       <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> JONES <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> BLAKE <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SCOTT <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span> ANALYST   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> KING  <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span> PRESIDENT <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> FORD  <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span> ANALYST   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> CLARK <span class=\"token operator\">|<\/span> <span class=\"token number\">2450.00<\/span> <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">6<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n<ul>\n<li>union all\u64cd\u4f5c\u7b26; \u5c06\u5de5\u8d44\u5927\u4e8e25000\u6216\u804c\u4f4d\u662fMANAGER\u7684\u4eba\u627e\u51fa\u6765 \u8be5\u64cd\u4f5c\u7b26\u7528\u4e8e\u53d6\u5f97\u4e24\u4e2a\u7ed3\u679c\u96c6\u7684\u5e76\u96c6\u3002\u5f53\u4f7f\u7528\u8be5\u64cd\u4f5c\u7b26\u65f6&#xff0c;\u4e0d\u4f1a\u53bb\u6389\u7ed3\u679c\u96c6\u4e2d\u7684\u91cd\u590d\u884c\u3002<\/li>\n<\/ul>\n<p>mysql<span class=\"token operator\">&gt;<\/span>  <span class=\"token keyword\">select<\/span> ename <span class=\"token punctuation\">,<\/span> sal <span class=\"token punctuation\">,<\/span> job <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> sal<span class=\"token operator\">&gt;<\/span><span class=\"token number\">2500<\/span> <span class=\"token keyword\">union<\/span> <span class=\"token keyword\">all<\/span><br \/>\n    <span class=\"token operator\">&#8211;<\/span><span class=\"token operator\">&gt;<\/span>  <span class=\"token keyword\">select<\/span> ename <span class=\"token punctuation\">,<\/span> sal <span class=\"token punctuation\">,<\/span> job <span class=\"token keyword\">from<\/span> emp <span class=\"token keyword\">where<\/span> job<span class=\"token operator\">&#061;<\/span><span class=\"token string\">&#039;MANAGER&#039;<\/span><span class=\"token punctuation\">;<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> ename <span class=\"token operator\">|<\/span> sal     <span class=\"token operator\">|<\/span> job       <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token operator\">|<\/span> JONES <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> BLAKE <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> SCOTT <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span> ANALYST   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> KING  <span class=\"token operator\">|<\/span> <span class=\"token number\">5000.00<\/span> <span class=\"token operator\">|<\/span> PRESIDENT <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> FORD  <span class=\"token operator\">|<\/span> <span class=\"token number\">3000.00<\/span> <span class=\"token operator\">|<\/span> ANALYST   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> JONES <span class=\"token operator\">|<\/span> <span class=\"token number\">2975.00<\/span> <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> BLAKE <span class=\"token operator\">|<\/span> <span class=\"token number\">2850.00<\/span> <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">|<\/span> CLARK <span class=\"token operator\">|<\/span> <span class=\"token number\">2450.00<\/span> <span class=\"token operator\">|<\/span> MANAGER   <span class=\"token operator\">|<\/span><br \/>\n<span class=\"token operator\">&#043;<\/span><span class=\"token comment\">&#8212;&#8212;-&#043;&#8212;&#8212;&#8212;&#043;&#8212;&#8212;&#8212;&#8211;&#043;<\/span><br \/>\n<span class=\"token number\">8<\/span> <span class=\"token keyword\">rows<\/span> <span class=\"token operator\">in<\/span> <span class=\"token keyword\">set<\/span> <span class=\"token punctuation\">(<\/span><span class=\"token number\">0.00<\/span> sec<span class=\"token punctuation\">)<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6587\u7ae0\u76ee\u5f55\u4e00\u3001\u524d\u60c5\u56de\u987e\u4e8c\u3001\u591a\u8868\u67e5\u8be2\u4e09\u3001\u81ea\u8fde\u63a5\u56db\u3001\u5b50\u67e5\u8be21.\u5355\u884c\u5b50\u67e5\u8be22.\u591a\u884c\u5b50\u67e5\u8be23.\u591a\u5217\u5b50\u67e5\u8be24.\u5728from\u5b50\u53e5\u4e2d\u4f7f\u7528\u5b50\u67e5\u8be2\u4e94\u3001\u5408\u5e76\u67e5\u8be2\u5728\u524d\u9762\u8868\u7684\u57fa\u7840\u4e0a\u8fdb\u884c\u64cd\u4f5c&#xff1a;<br \/>\nmysql&gt; show tables;<br \/>\n&#8212;&#8212;&#8212;&#8212;&#8212;&#8211;<br \/>\n| Tables_in_scott |<br \/>\n&#8212;&#8212;&#8212;&#8212;&#8212;&#8211;<br \/>\n| dept            |<br \/>\n| emp             |<br \/>\n| salgrade        |<br 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