{"id":70905,"date":"2026-02-02T19:16:39","date_gmt":"2026-02-02T11:16:39","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/70905.html"},"modified":"2026-02-02T19:16:39","modified_gmt":"2026-02-02T11:16:39","slug":"mysql%e5%a4%9a%e8%a1%a8%e8%bf%9e%e6%8e%a5%e6%9f%a5%e8%af%a2%e8%af%a6%e8%a7%a3","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/70905.html","title":{"rendered":"MySQL\u591a\u8868\u8fde\u63a5\u67e5\u8be2\u8be6\u89e3"},"content":{"rendered":"<h2>MySQL\u591a\u8868\u8fde\u63a5\u67e5\u8be2\u8be6\u89e3&#xff1a;INNER JOIN\u3001LEFT JOIN\u3001RIGHT JOIN\u4e0eFULL JOIN<\/h2>\n<p>\u5728MySQL\u6570\u636e\u5e93\u64cd\u4f5c\u4e2d&#xff0c;\u5355\u8868\u67e5\u8be2\u5f80\u5f80\u65e0\u6cd5\u6ee1\u8db3\u590d\u6742\u7684\u4e1a\u52a1\u9700\u6c42&#xff0c;\u591a\u8868\u8fde\u63a5\u67e5\u8be2\u662f\u5b9e\u73b0\u6570\u636e\u5173\u8054\u5206\u6790\u7684\u6838\u5fc3\u624b\u6bb5\u3002\u5e38\u89c1\u7684\u591a\u8868\u8fde\u63a5\u65b9\u5f0f\u5305\u62ec INNER JOIN\u3001LEFT JOIN\u3001RIGHT JOIN \u548c FULL JOIN&#xff0c;\u5b83\u4eec\u5404\u81ea\u9002\u7528\u4e8e\u4e0d\u540c\u7684\u4e1a\u52a1\u573a\u666f&#xff0c;\u638c\u63e1\u8fd9\u4e9b\u8fde\u63a5\u65b9\u5f0f\u80fd\u5927\u5e45\u63d0\u5347\u6570\u636e\u67e5\u8be2\u7684\u7075\u6d3b\u6027\u548c\u6548\u7387\u3002<\/p>\n<h3>\u4e00\u3001\u591a\u8868\u8fde\u63a5\u7684\u57fa\u7840\u6982\u5ff5<\/h3>\n<p>\u591a\u8868\u8fde\u63a5\u7684\u672c\u8d28\u662f\u57fa\u4e8e\u4e00\u4e2a\u6216\u591a\u4e2a\u5171\u540c\u5b57\u6bb5&#xff0c;\u5c06\u591a\u4e2a\u8868\u7684\u6570\u636e\u5173\u8054\u8d77\u6765&#xff0c;\u5f62\u6210\u4e00\u4e2a\u5305\u542b\u8054\u5408\u4fe1\u606f\u7684\u7ed3\u679c\u96c6\u3002\u8fde\u63a5\u67e5\u8be2\u7684\u6838\u5fc3\u662f\u8fde\u63a5\u6761\u4ef6&#xff0c;\u901a\u5e38\u4ee5\u4e24\u4e2a\u8868\u7684\u5173\u8054\u5b57\u6bb5&#xff08;\u5982\u4e3b\u952e\u4e0e\u5916\u952e&#xff09;\u4f5c\u4e3a\u5339\u914d\u4f9d\u636e\u3002<\/p>\n<p>\u4e3a\u4e86\u65b9\u4fbf\u540e\u7eed\u793a\u4f8b\u6f14\u793a&#xff0c;\u6211\u4eec\u5148\u521b\u5efa\u4e24\u4e2a\u6d4b\u8bd5\u8868\u5e76\u63d2\u5165\u6570\u636e&#xff1a;<\/p>\n<h4>1. \u90e8\u95e8\u8868 dept&#xff08;\u7236\u8868&#xff09;<\/h4>\n<p>CREATE TABLE &#096;dept&#096; (<br \/>\n    &#096;dept_id&#096; INT PRIMARY KEY AUTO_INCREMENT COMMENT &#039;\u90e8\u95e8ID&#039;,<br \/>\n    &#096;dept_name&#096; VARCHAR(50) NOT NULL COMMENT &#039;\u90e8\u95e8\u540d\u79f0&#039;<br \/>\n);<br \/>\nINSERT INTO &#096;dept&#096; VALUES (1, &#039;\u7814\u53d1\u90e8&#039;), (2, &#039;\u5e02\u573a\u90e8&#039;), (3, &#039;\u8d22\u52a1\u90e8&#039;);<\/p>\n<h4>2. \u5458\u5de5\u8868 emp&#xff08;\u5b50\u8868&#xff09;<\/h4>\n<p>CREATE TABLE &#096;emp&#096; (<br \/>\n    &#096;emp_id&#096; INT PRIMARY KEY AUTO_INCREMENT COMMENT &#039;\u5458\u5de5ID&#039;,<br \/>\n    &#096;emp_name&#096; VARCHAR(50) NOT NULL COMMENT &#039;\u5458\u5de5\u59d3\u540d&#039;,<br \/>\n    &#096;dept_id&#096; INT COMMENT &#039;\u6240\u5c5e\u90e8\u95e8ID&#039;,<br \/>\n    FOREIGN KEY (&#096;dept_id&#096;) REFERENCES &#096;dept&#096;(&#096;dept_id&#096;)<br \/>\n);<br \/>\nINSERT INTO &#096;emp&#096; VALUES (1, &#039;\u5f20\u4e09&#039;, 1), (2, &#039;\u674e\u56db&#039;, 1), (3, &#039;\u738b\u4e94&#039;, 2), (4, &#039;\u8d75\u516d&#039;, NULL);<\/p>\n<h3>\u4e8c\u3001\u5185\u8fde\u63a5&#xff1a;INNER JOIN<\/h3>\n<p>INNER JOIN \u4e5f\u53eb\u7b49\u503c\u8fde\u63a5&#xff0c;\u662f\u6700\u5e38\u7528\u7684\u8fde\u63a5\u65b9\u5f0f\u3002\u5b83\u53ea\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u6ee1\u8db3\u8fde\u63a5\u6761\u4ef6\u7684\u5339\u914d\u884c&#xff0c;\u4e0d\u5339\u914d\u7684\u884c\u5c06\u88ab\u8fc7\u6ee4\u6389\u3002<\/p>\n<h4>1. \u8bed\u6cd5\u683c\u5f0f<\/h4>\n<p>SELECT \u5b57\u6bb5\u5217\u8868<br \/>\nFROM \u88681<br \/>\nINNER JOIN \u88682<br \/>\nON \u88681.\u5173\u8054\u5b57\u6bb5 &#061; \u88682.\u5173\u8054\u5b57\u6bb5;<\/p>\n<h4>2. \u6838\u5fc3\u7279\u70b9<\/h4>\n<ul>\n<li>\u53ea\u4fdd\u7559\u4e24\u4e2a\u8868\u7684\u4ea4\u96c6\u6570\u636e\u3002<\/li>\n<li>\u53ef\u7701\u7565 INNER \u5173\u952e\u5b57&#xff0c;\u76f4\u63a5\u5199 JOIN\u3002<\/li>\n<\/ul>\n<h4>3. \u5b9e\u6218\u793a\u4f8b<\/h4>\n<p>\u67e5\u8be2\u6bcf\u4e2a\u5458\u5de5\u7684\u59d3\u540d\u53ca\u5176\u6240\u5c5e\u90e8\u95e8\u540d\u79f0&#xff1a;<\/p>\n<p>SELECT e.emp_name, d.dept_name<br \/>\nFROM emp e<br \/>\nINNER JOIN dept d<br \/>\nON e.dept_id &#061; d.dept_id;<\/p>\n<h4>4. \u6267\u884c\u7ed3\u679c<\/h4>\n<table>\n<tr>emp_namedept_name<\/tr>\n<tbody>\n<tr>\n<td>\u5f20\u4e09<\/td>\n<td>\u7814\u53d1\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u674e\u56db<\/td>\n<td>\u7814\u53d1\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u738b\u4e94<\/td>\n<td>\u5e02\u573a\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u8bf4\u660e&#xff1a;\u5458\u5de5\u8d75\u516d\u7684 dept_id \u4e3a NULL&#xff0c;\u6ca1\u6709\u5339\u914d\u7684\u90e8\u95e8\u6570\u636e&#xff0c;\u56e0\u6b64\u4e0d\u663e\u793a&#xff1b;\u8d22\u52a1\u90e8\u6ca1\u6709\u5bf9\u5e94\u7684\u5458\u5de5\u6570\u636e&#xff0c;\u4e5f\u4e0d\u663e\u793a\u3002<\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>\u4e09\u3001\u5de6\u8fde\u63a5&#xff1a;LEFT JOIN<\/h3>\n<p>LEFT JOIN \u4e5f\u53eb\u5de6\u5916\u8fde\u63a5&#xff0c;\u5b83\u4ee5\u5de6\u8868\u4e3a\u57fa\u51c6&#xff0c;\u8fd4\u56de\u5de6\u8868\u7684\u6240\u6709\u884c&#xff0c;\u4ee5\u53ca\u53f3\u8868\u4e2d\u6ee1\u8db3\u8fde\u63a5\u6761\u4ef6\u7684\u5339\u914d\u884c\u3002\u5982\u679c\u53f3\u8868\u6ca1\u6709\u5339\u914d\u7684\u6570\u636e&#xff0c;\u5bf9\u5e94\u7684\u5b57\u6bb5\u5c06\u586b\u5145\u4e3a NULL\u3002<\/p>\n<h4>1. \u8bed\u6cd5\u683c\u5f0f<\/h4>\n<p>SELECT \u5b57\u6bb5\u5217\u8868<br \/>\nFROM \u88681<br \/>\nLEFT JOIN \u88682<br \/>\nON \u88681.\u5173\u8054\u5b57\u6bb5 &#061; \u88682.\u5173\u8054\u5b57\u6bb5;<\/p>\n<h4>2. \u6838\u5fc3\u7279\u70b9<\/h4>\n<ul>\n<li>\u5de6\u8868\u6570\u636e\u5168\u90e8\u4fdd\u7559&#xff0c;\u53f3\u8868\u5339\u914d\u4e0d\u5230\u5219\u8865 NULL\u3002<\/li>\n<li>LEFT JOIN \u7b49\u4ef7\u4e8e LEFT OUTER JOIN&#xff0c;OUTER \u53ef\u7701\u7565\u3002<\/li>\n<\/ul>\n<h4>3. \u5b9e\u6218\u793a\u4f8b<\/h4>\n<p>\u67e5\u8be2\u6240\u6709\u5458\u5de5\u7684\u59d3\u540d\u53ca\u5176\u6240\u5c5e\u90e8\u95e8\u540d\u79f0&#xff08;\u5305\u62ec\u65e0\u90e8\u95e8\u7684\u5458\u5de5&#xff09;&#xff1a;<\/p>\n<p>SELECT e.emp_name, d.dept_name<br \/>\nFROM emp e<br \/>\nLEFT JOIN dept d<br \/>\nON e.dept_id &#061; d.dept_id;<\/p>\n<h4>4. \u6267\u884c\u7ed3\u679c<\/h4>\n<table>\n<tr>emp_namedept_name<\/tr>\n<tbody>\n<tr>\n<td>\u5f20\u4e09<\/td>\n<td>\u7814\u53d1\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u674e\u56db<\/td>\n<td>\u7814\u53d1\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u738b\u4e94<\/td>\n<td>\u5e02\u573a\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u8d75\u516d<\/td>\n<td>NULL<\/td>\n<\/tr>\n<tr>\n<td>\u8bf4\u660e&#xff1a;\u5de6\u8868 emp \u4e2d\u7684\u6240\u6709\u5458\u5de5\u90fd\u88ab\u8fd4\u56de&#xff0c;\u8d75\u516d\u6ca1\u6709\u5bf9\u5e94\u7684\u90e8\u95e8&#xff0c;dept_name \u586b\u5145\u4e3a NULL\u3002<\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>\u56db\u3001\u53f3\u8fde\u63a5&#xff1a;RIGHT JOIN<\/h3>\n<p>RIGHT JOIN \u4e5f\u53eb\u53f3\u5916\u8fde\u63a5&#xff0c;\u5b83\u4ee5\u53f3\u8868\u4e3a\u57fa\u51c6&#xff0c;\u8fd4\u56de\u53f3\u8868\u7684\u6240\u6709\u884c&#xff0c;\u4ee5\u53ca\u5de6\u8868\u4e2d\u6ee1\u8db3\u8fde\u63a5\u6761\u4ef6\u7684\u5339\u914d\u884c\u3002\u5982\u679c\u5de6\u8868\u6ca1\u6709\u5339\u914d\u7684\u6570\u636e&#xff0c;\u5bf9\u5e94\u7684\u5b57\u6bb5\u5c06\u586b\u5145\u4e3a NULL\u3002<\/p>\n<h4>1. \u8bed\u6cd5\u683c\u5f0f<\/h4>\n<p>SELECT \u5b57\u6bb5\u5217\u8868<br \/>\nFROM \u88681<br \/>\nRIGHT JOIN \u88682<br \/>\nON \u88681.\u5173\u8054\u5b57\u6bb5 &#061; \u88682.\u5173\u8054\u5b57\u6bb5;<\/p>\n<h4>2. \u6838\u5fc3\u7279\u70b9<\/h4>\n<ul>\n<li>\u53f3\u8868\u6570\u636e\u5168\u90e8\u4fdd\u7559&#xff0c;\u5de6\u8868\u5339\u914d\u4e0d\u5230\u5219\u8865 NULL\u3002<\/li>\n<li>RIGHT JOIN \u7b49\u4ef7\u4e8e RIGHT OUTER JOIN&#xff0c;OUTER \u53ef\u7701\u7565\u3002<\/li>\n<\/ul>\n<h4>3. \u5b9e\u6218\u793a\u4f8b<\/h4>\n<p>\u67e5\u8be2\u6240\u6709\u90e8\u95e8\u7684\u540d\u79f0\u53ca\u5176\u5bf9\u5e94\u7684\u5458\u5de5\u59d3\u540d&#xff08;\u5305\u62ec\u65e0\u5458\u5de5\u7684\u90e8\u95e8&#xff09;&#xff1a;<\/p>\n<p>SELECT e.emp_name, d.dept_name<br \/>\nFROM emp e<br \/>\nRIGHT JOIN dept d<br \/>\nON e.dept_id &#061; d.dept_id;<\/p>\n<h4>4. \u6267\u884c\u7ed3\u679c<\/h4>\n<table>\n<tr>emp_namedept_name<\/tr>\n<tbody>\n<tr>\n<td>\u5f20\u4e09<\/td>\n<td>\u7814\u53d1\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u674e\u56db<\/td>\n<td>\u7814\u53d1\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u738b\u4e94<\/td>\n<td>\u5e02\u573a\u90e8<\/td>\n<\/tr>\n<tr>\n<td>NULL<\/td>\n<td>\u8d22\u52a1\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u8bf4\u660e&#xff1a;\u53f3\u8868 dept \u4e2d\u7684\u6240\u6709\u90e8\u95e8\u90fd\u88ab\u8fd4\u56de&#xff0c;\u8d22\u52a1\u90e8\u6ca1\u6709\u5bf9\u5e94\u7684\u5458\u5de5&#xff0c;emp_name \u586b\u5145\u4e3a NULL\u3002<\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>\u4e94\u3001\u5168\u8fde\u63a5&#xff1a;FULL JOIN<\/h3>\n<p>FULL JOIN \u4e5f\u53eb\u5168\u5916\u8fde\u63a5&#xff0c;\u5b83\u8fd4\u56de\u5de6\u8868\u548c\u53f3\u8868\u7684\u6240\u6709\u884c\u3002\u5f53\u67d0\u4e00\u884c\u5728\u53e6\u4e00\u4e2a\u8868\u4e2d\u6ca1\u6709\u5339\u914d\u6570\u636e\u65f6&#xff0c;\u5bf9\u5e94\u7684\u5b57\u6bb5\u586b\u5145\u4e3a NULL\u3002<\/p>\n<h4>1. \u8bed\u6cd5\u683c\u5f0f<\/h4>\n<p>SELECT \u5b57\u6bb5\u5217\u8868<br \/>\nFROM \u88681<br \/>\nFULL JOIN \u88682<br \/>\nON \u88681.\u5173\u8054\u5b57\u6bb5 &#061; \u88682.\u5173\u8054\u5b57\u6bb5;<\/p>\n<h4>2. \u6838\u5fc3\u7279\u70b9<\/h4>\n<ul>\n<li>\u4fdd\u7559\u4e24\u4e2a\u8868\u7684\u6240\u6709\u6570\u636e&#xff0c;\u7b49\u4ef7\u4e8e LEFT JOIN \u548c RIGHT JOIN \u7684\u5e76\u96c6\u3002<\/li>\n<li>\u6ce8\u610f&#xff1a;MySQL \u539f\u751f\u4e0d\u652f\u6301 FULL JOIN&#xff0c;\u9700\u8981\u901a\u8fc7 UNION \u5173\u952e\u5b57\u8054\u5408 LEFT JOIN \u548c RIGHT JOIN \u7684\u7ed3\u679c\u6765\u5b9e\u73b0\u3002<\/li>\n<\/ul>\n<h4>3. \u5b9e\u6218\u793a\u4f8b<\/h4>\n<p>\u67e5\u8be2\u6240\u6709\u5458\u5de5\u548c\u6240\u6709\u90e8\u95e8\u7684\u5173\u8054\u6570\u636e&#xff08;\u5305\u62ec\u65e0\u90e8\u95e8\u7684\u5458\u5de5\u548c\u65e0\u5458\u5de5\u7684\u90e8\u95e8&#xff09;&#xff1a;<\/p>\n<p>&#8212; \u5de6\u8fde\u63a5\u7ed3\u679c<br \/>\nSELECT e.emp_name, d.dept_name<br \/>\nFROM emp e<br \/>\nLEFT JOIN dept d<br \/>\nON e.dept_id &#061; d.dept_id<br \/>\nUNION<br \/>\n&#8212; \u53f3\u8fde\u63a5\u7ed3\u679c&#xff08;\u6392\u9664\u91cd\u590d\u6570\u636e&#xff09;<br \/>\nSELECT e.emp_name, d.dept_name<br \/>\nFROM emp e<br \/>\nRIGHT JOIN dept d<br \/>\nON e.dept_id &#061; d.dept_id;<\/p>\n<h4>4. \u6267\u884c\u7ed3\u679c<\/h4>\n<table>\n<tr>emp_namedept_name<\/tr>\n<tbody>\n<tr>\n<td>\u5f20\u4e09<\/td>\n<td>\u7814\u53d1\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u674e\u56db<\/td>\n<td>\u7814\u53d1\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u738b\u4e94<\/td>\n<td>\u5e02\u573a\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u8d75\u516d<\/td>\n<td>NULL<\/td>\n<\/tr>\n<tr>\n<td>NULL<\/td>\n<td>\u8d22\u52a1\u90e8<\/td>\n<\/tr>\n<tr>\n<td>\u8bf4\u660e&#xff1a;UNION \u4f1a\u81ea\u52a8\u53bb\u91cd&#xff0c;\u786e\u4fdd\u7ed3\u679c\u96c6\u4e2d\u6ca1\u6709\u91cd\u590d\u884c\u3002<\/td>\n<td><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>\u516d\u3001\u56db\u79cd\u8fde\u63a5\u65b9\u5f0f\u7684\u6838\u5fc3\u533a\u522b<\/h3>\n<table>\n<tr>\u8fde\u63a5\u65b9\u5f0f\u6838\u5fc3\u903b\u8f91\u8fd4\u56de\u6570\u636e\u8303\u56f4MySQL\u652f\u6301\u60c5\u51b5<\/tr>\n<tbody>\n<tr>\n<td>INNER JOIN<\/td>\n<td>\u53ea\u4fdd\u7559\u4e24\u8868\u5339\u914d\u7684\u6570\u636e<\/td>\n<td>\u4e24\u8868\u4ea4\u96c6<\/td>\n<td>\u652f\u6301<\/td>\n<\/tr>\n<tr>\n<td>LEFT JOIN<\/td>\n<td>\u4fdd\u7559\u5de6\u8868\u5168\u90e8\u6570\u636e&#xff0c;\u53f3\u8868\u5339\u914d\u8865\u5168<\/td>\n<td>\u5de6\u8868\u5168\u90e8 &#043; \u53f3\u8868\u5339\u914d\u90e8\u5206<\/td>\n<td>\u652f\u6301<\/td>\n<\/tr>\n<tr>\n<td>RIGHT JOIN<\/td>\n<td>\u4fdd\u7559\u53f3\u8868\u5168\u90e8\u6570\u636e&#xff0c;\u5de6\u8868\u5339\u914d\u8865\u5168<\/td>\n<td>\u53f3\u8868\u5168\u90e8 &#043; \u5de6\u8868\u5339\u914d\u90e8\u5206<\/td>\n<td>\u652f\u6301<\/td>\n<\/tr>\n<tr>\n<td>FULL 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