\u4ecb\u7ecdSQL<\/h2>\n（1）\u4ec0\u4e48SQL<\/h4>\n
SQL，\u662f\u7528\u4e8e\u7ba1\u7406\u548c\u64cd\u4f5c\u5173\u7cfb\u578b\u6570\u636e\u5e93\u7684\u6807\u51c6\u7f16\u7a0b\u8bed\u8a00，\u6838\u5fc3\u4f5c\u7528\u662f\u5b9e\u73b0\u6570\u636e\u7684\u67e5\u8be2\u3001\u63d2\u5165\u3001\u66f4\u65b0\u3001\u5220\u9664\u7b49\u64cd\u4f5c，\u51e0\u4e4e\u6240\u6709\u5173\u7cfb\u578b\u6570\u636e\u5e93（\u5982MySQL\u3001Oracle\u3001SQL Server）\u90fd\u4f9d\u8d56\u5b83\u5de5\u4f5c\u3002<\/p>\n
\u7b80\u5355\u6765\u8bf4，\u5b83\u5c31\u50cf\u201c\u6570\u636e\u5e93\u7684\u6307\u4ee4\u9065\u63a7\u5668\u201d\u2014\u2014\u6bd4\u5982\u60f3\u4ece\u201c\u7528\u6237\u8868\u201d\u91cc\u627e\u51fa\u6240\u6709\u5e74\u9f84\u5c0f\u4e8e30\u5c81\u7684\u4eba，\u7528SQL\u5199\u4e00\u53e5\u00a0SELECT * FROM \u7528\u6237\u8868 WHERE \u5e74\u9f84 < 30\u00a0\u5c31\u80fd\u5feb\u901f\u5b9e\u73b0，\u65e0\u9700\u590d\u6742\u7f16\u7a0b\u3002<\/p>\n
（2）MySQL\u76f8\u5173\u3010+\u521b\u5efasql\u6570\u636e\u5e93\u3011<\/h4>\n
\u3010\u5229\u7528\u5c0f\u76ae\u9762\u677f，\u5341\u5206\u5bb9\u6613\u3002\u3002\u3011<\/p>\n
\u5982\u679c\u7528docker\u642d\u5efa\u7684\u8bdd，\u53ef\u4ee5\u770b\u8fd9\u4e2a\u5927\u4f6c<\/p>\n
\u3010SQL\u6ce8\u5165\u3011\u5c0f\u767d\u624b\u628a\u624b\u5165\u95e8SQL\u6ce8\u51651-\u6570\u636e\u5e93\u57fa\u7840-CSDN\u535a\u5ba2<\/p>\n
\u5c0f\u76ae\u9762\u677f\u7684sql\u642d\u5efa\u65b9\u5f0f\u53ef\u4ee5\u770b\u8fd9\u4e2a\u5927\u4f6c<\/p>\n
\u5229\u7528\u5c0f\u76ae\u9762\u677f\u81ea\u5e26\u5de5\u5177\u642d\u5efa\u6570\u636e\u5e93_phpstudy\u5c0f\u76ae\u6570\u636e\u5e93\u600e\u4e48\u7528-CSDN\u535a\u5ba2<\/p>\n
\u3010\u6709\u4e00\u4e9b\u521b\u5efa\u548c\u67e5\u8be2\u4e0d\u592a\u4e00\u6837\u3011<\/p>\n
\u5b89\u88c5\u4e86\u4e2aSQL，\u521b\u5efa\u4e86\u6570\u636e\u5e93<\/p>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063233-69746781e8257.png\")
<\/p>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063237-697467858c908.png\")
<\/p>\n
MySQL\u9ed8\u8ba4\u5728\u6570\u636e\u5e93\u4e2d\u5b58\u653e\u4e00\u4e2a"information_schema"\u7684\u6570\u636e\u5e93，\u662fmysql\u81ea\u5e26\u7684\u4e00\u4e2a\u4fe1\u606f\u6570\u636e\u5e93，\u4fdd\u5b58\u7740\u5173\u4e8eMySQL\u670d\u52a1\u5668\u6240\u7ef4\u62a4\u7684\u6240\u6709\u5176\u4ed6\u6570\u636e\u5e93\u7684\u4fe1\u606f\u3002<\/p>\n
（3）MySQL\u67e5\u8be2\u8bed\u53e5<\/h4>\n1. \u4e0d\u77e5\u9053\u4efb\u4f55\u6761\u4ef6\u65f6\u5982\u4e0b\u6240\u793a<\/h5>\n
select \u67e5\u8be2\u7684\u5b57\u6bb5\u540d from \u5e93\u540d.\u8868\u540d<\/p>\n
2. \u5df2\u77e5\u4e00\u6761\u6761\u4ef6\u65f6\u5982\u4e0b\u6240\u793a<\/h5>\n
select \u8981\u67e5\u8be2\u7684\u5b57\u6bb5\u540d from \u5e93\u540d.\u8868\u540d where \u5df2\u77e5\u6761\u4ef6\u7684\u5b57\u6bb5\u540d='\u5df2\u77e5\u6761\u4ef6\u7684\u503c'<\/p>\n
\u793a\u4f8b：sql=select name from users where id='1';<\/p>\n
3. show\u7684\u4f7f\u7528\u547d\u4ee4<\/h5>\n\u2170. show databases;\u67e5\u770b\u6240\u6709\u6570\u636e\u5e93<\/h6>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063240-69746788656ce.png\")
<\/p>\n
information_schema\u5e93: \u662f\u4fe1\u606f\u6570\u636e\u5e93，\u5176\u4e2d\u4fdd\u5b58\u7740\u5173\u4e8eMySQL\u670d\u52a1\u5668\u6240\u7ef4\u62a4\u7684\u6240\u6709\u5176\u4ed6\u6570\u636e\u5e93\u7684\u4fe1\u606f\u6bd4\u5982\u6570\u636e\u5e93\u540d，\u6570\u636e\u5e93\u8868，\u8868\u5b57\u6bb5\u7684\u6570\u636e\u7c7b\u578b\u4e0e\u8bbf\u95ee\u6743\u9650\u7b49\u3002Web\u6e17\u900f\u8fc7\u7a0b\u4e2d\u7528\u9014\u5f88\u5927\u3002<\/p>\n
mysql \u5e93: MySQL\u7684\u6838\u5fc3\u6570\u636e\u5e93，\u4e3b\u8981\u8d1f\u8d23\u5b58\u50a8\u6570\u636e\u5e93\u7684\u7528\u6237\u3001\u6743\u9650\u8bbe\u7f6e\u3001 \u5173\u952e\u5b57\u7b49mysql\u81ea\u5df1\u9700\u8981\u4f7f\u7528\u7684\u63a7\u5236\u548c\u7ba1\u7406\u4fe1\u606f\u3002<\/p>\n
performance_schema \u5e93: \u5185\u5b58\u6570\u636e\u5e93，\u6570\u636e\u653e\u5728\u5185\u5b58\u4e2d\u76f4\u63a5\u64cd\u4f5c\u7684\u6570\u636e\u5e93\u3002\u76f8\u5bf9\u4e8e\u78c1\u76d8，\u5185\u5b58\u7684\u6570\u636e\u8bfb\u5199\u901f\u5ea6\u8981\u9ad8\u51fa\u51e0\u4e2a\u6570\u91cf\u7ea7，\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\u76f8 \u6bd4\u4ece\u78c1\u76d8\u4e0a\u8bbf\u95ee\u80fd\u591f\u6781\u5927\u5730\u63d0\u9ad8\u5e94\u7528\u7684\u6027\u80fd\u3002<\/p>\n
sys \u5e93: \u901a\u8fc7\u8fd9\u4e2a\u6570\u636e\u5e93\u6570\u636e\u5e93，\u53ef\u4ee5\u67e5\u8be2\u8c01\u4f7f\u7528\u4e86\u6700\u591a\u7684\u8d44\u6e90 \u57fa\u4e8eIP\u6216\u662f\u7528\u6237\u3002\u54ea\u5f20\u8868\u88ab\u8bbf\u95ee\u8fc7\u6700\u591a\u7b49\u7b49\u4fe1\u606f\u3002<\/p>\n
\u2171. show tables from information_schema;\u67e5\u770b\u8868<\/h6>\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063241-6974678971a8b.png\")
<\/p>\n
SCHEMATA \u8868: \u63d0\u4f9b\u4e86\u5f53\u524dMySQL\u5b9e\u4f8b\u4e2d\u6240\u6709\u7684\u6570\u636e\u5e93\u4fe1\u606f，show databases \u7ed3\u679c\u53d6\u4e4b\u6b64\u8868 TABLES \u8868:\u63d0\u4f9b\u4e86\u5173\u4e8e\u6570\u636e\u5e93\u4e2d\u8868\u7684\u4fe1\u606f COLUMNS \u8868: \u63d0\u4f9b\u4e86\u8868\u4e2d\u7684\u5217\u4fe1\u606f，\u8be6\u7ec6\u63cf\u8ff0\u4e86\u67d0\u5f20\u8868\u7684\u6240\u6709\u5217\u5df2\u7ecf\u6bcf\u4e2a\u5217\u7684\u4fe1\u606f<\/p>\n
\u2172. \u67e5\u770b\u4f60\u67d0\u4e00\u4e2a\u6570\u636e\u5e93\u4e2d\u6709\u54ea\u4e9b\u8868<\/h6>\n
\u3010\u56e0\u4e3a\u6211\u4f7f\u7528\u7684\u662f\u5c0f\u76ae\u9762\u677f\u7684，\u6240\u4ee5\u53ef\u4ee5\u76f4\u63a5\u9501\u5b9a\u662f\u54ea\u4e00\u4e2a\u5e93，，\u6240\u4ee5use mysql;\u65e0\u9700\u3011<\/p>\n
\u7b2c\u4e00\u79cd: \u9996\u5148\u4f7f\u7528\u5e93use mysql; \u7136\u540e\u67e5\u770b\u8868show tables;<\/p>\n
\u7b2c\u4e8c\u79cd: show tables from mysql<\/p>\n
4. select\u7279\u6b8a\u67e5\u8be2\u7528\u6cd5<\/h5>\n\u2170. select now();：\u67e5\u770b\u65f6\u95f4<\/h6>\n
\u6ce8\u610f：\u8fd0\u884c\u540e\u51fa\u73b0\u95ee\u9898，now \u540e\u9762\u4e0d\u80fd\u6709\u7a7a\u683c<\/p>\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063241-69746789ed0ba.png\")
<\/p>\n
\u2171. select database();：\u67e5\u770b\u5f53\u524d\u9009\u62e9\u7684\u662f\u54ea\u4e2a\u6570\u636e\u5e93<\/h6>\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063242-6974678ad7c64.png\")
<\/p>\n
\u2172. select version();：\u67e5\u770b\u7248\u672c<\/h6>\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063243-6974678bb473d.png\")
<\/p>\n
\u2173. select user();：\u67e5\u770b\u5f53\u524d\u767b\u5f55\u6570\u636e\u5e93\u7684\u7528\u6237<\/h6>\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063244-6974678c9a6da.png\")
<\/p>\n
\u2174. select @@datadir;：\u67e5\u770b\u6570\u636e\u8def\u5f84<\/h6>\n\u2175. select @@basedir;：\u67e5\u770bmysql\u5b89\u88c5\u8def\u5f84<\/h6>\n\u2176. select @@version_compile_os;：\u67e5\u770bmysql\u5b89\u88c5\u7684\u7cfb\u7edf<\/h6>\n\u2177. select group_concat(\u5b57\u6bb5\u540d)：\u628a\u6570\u636e\u5e93\u4e2d\u7684\u67d0\u5217\u6570\u636e\u6216\u67d0\u51e0\u5217\u6570\u636e\u5408\u5e76\u4e3a\u4e00\u4e2a\u5b57\u7b26\u4e32<\/h6>\n
\u2176. select @@version_compile_os;：\u67e5\u770bmysql\u5b89\u88c5\u7684\u7cfb\u7edf<\/h6>\n\u2177. select group_concat(\u5b57\u6bb5\u540d)：\u628a\u6570\u636e\u5e93\u4e2d\u7684\u67d0\u5217\u6570\u636e\u6216\u67d0\u51e0\u5217\u6570\u636e\u5408\u5e76\u4e3a\u4e00\u4e2a\u5b57\u7b26\u4e32<\/h6>\n
group_concat\u51fd\u6570\u662f\u5c06\u67e5\u8be2\u5230\u7684\u6bcf\u884c\u7ed3\u679c\u4ee5\u67d0\u4e2a\u5b57\u6bb5\u540d\u8fdb\u884c\u5408\u5e76，\u6bcf\u4e00\u884c\u5408\u5e76\u7684\u7ed3\u679c\u4ee5\u9017\u53f7\u5206\u9694\u5f00<\/p>\n
\u2178. \u67e5\u8be2\u6570\u636e<\/h6>\n
\u67e5\u6240\u6709\u5b57\u6bb5select * from mysql.user;<\/p>\n
\u3010*\u662f\u6240\u6709~~~\u3011<\/p>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063245-6974678d56cea.png\")
<\/p>\n
\u67e5\u67d0\u51e0\u4e2a\u6bd4\u8f83\u91cd\u8981\u7684\u5b57\u6bb5select user,host from mysql.user;<\/p>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063245-6974678de5baa.png\")
<\/p>\n
\n
\n
5. limit \u5206\u9875\u67e5\u8be2<\/h5>\n
1. \u8bed\u6cd5：limit \u5f00\u59cb\u7684\u7d22\u5f15,\u6bcf\u9875\u67e5\u8be2\u7684\u6761\u6570; 2. \u516c\u5f0f：\u5f00\u59cb\u7684\u7d22\u5f15 = （\u5f53\u524d\u7684\u9875\u7801 – 1） * \u6bcf\u9875\u663e\u793a\u7684\u6761\u6570 3. limit \u662f\u4e00\u4e2aMySQL"\u65b9\u8a00"<\/p>\n
— \u6bcf\u9875\u663e\u793a3\u6761\u8bb0\u5f55 <\/p>\n
SELECT * FROM student LIMIT 0,3; — \u7b2c1\u9875
\n\/\/\u4ece\u7b2c 0 \u6761\u8bb0\u5f55\u5f00\u59cb（\u5373\u7b2c\u4e00\u6761\u8bb0\u5f55），\u53d6 3 \u6761\u8bb0\u5f55\u3002<\/p>\n
SELECT * FROM student LIMIT 3,3; — \u7b2c2\u9875
\n\/\/\u4ece\u7b2c 3 \u6761\u8bb0\u5f55\u5f00\u59cb（\u7d22\u5f15\u4ece 0 \u5f00\u59cb，\u7b2c 3 \u6761\u662f\u7b2c 4 \u6761\u8bb0\u5f55），\u53d6 3 \u6761\u8bb0\u5f55\u3002<\/p>\n
SELECT * FROM student LIMIT 6,3; — \u7b2c3\u9875
\n\/\/\u4ece\u7b2c7\u6761\u8bb0\u5f55\u5f00\u59cb，\u53d63\u6761\u8bb0\u5f55 <\/p>\n
\u2170. limit\u7528\u6cd5<\/h6>\n
\u5728\u6570\u636e\u5e93\u4e2d，\u5f53\u8868\u4e2d\u7684\u6570\u636e\u91cf\u5f88\u5927\u65f6，\u4e00\u6b21\u6027\u67e5\u8be2\u6240\u6709\u6570\u636e\u53ef\u80fd\u4f1a\u5bfc\u81f4\u6027\u80fd\u95ee\u9898\u6216\u4e0d\u65b9\u4fbf\u67e5\u770b\u3002\u56e0\u6b64，\u6211\u4eec\u901a\u5e38\u4f1a\u5c06\u6570\u636e\u5206\u6210\u201c\u9875\u201d，\u6bcf\u6b21\u53ea\u67e5\u8be2\u4e00\u9875\u7684\u6570\u636e\u3002<\/p>\n
LIMIT \u662f\u5b9e\u73b0\u5206\u9875\u67e5\u8be2\u7684\u5173\u952e\u5de5\u5177\u3002<\/p>\n
SELECT * FROM \u8868\u540d LIMIT \u8d77\u59cb\u4f4d\u7f6e, \u6bcf\u9875\u8bb0\u5f55\u6570;
\n\/\/\u8d77\u59cb\u4f4d\u7f6e：
\n\u8868\u793a\u4ece\u7b2c\u51e0\u6761\u8bb0\u5f55\u5f00\u59cb（\u7d22\u5f15\u4ece 0 \u5f00\u59cb）\u3002
\n\/\/\u6bcf\u9875\u8bb0\u5f55\u6570：
\n\u8868\u793a\u6bcf\u9875\u663e\u793a\u591a\u5c11\u6761\u8bb0\u5f55\u3002 <\/p>\n
\u6ce8\u610f\u4e8b\u9879<\/p>\n
- \n
- \n
- \n
- LIMIT \u7684\u7b2c\u4e00\u4e2a\u53c2\u6570\u662f\u4ece 0 \u5f00\u59cb\u8ba1\u6570\u7684，\u8868\u793a\u504f\u79fb\u91cf\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \u8d85\u51fa\u8303\u56f4\u7684\u60c5\u51b5：<\/li>\n
- \n
- \n
- \n
- \u5982\u679c\u8d77\u59cb\u4f4d\u7f6e\u8d85\u51fa\u4e86\u8868\u4e2d\u7684\u603b\u8bb0\u5f55\u6570，\u67e5\u8be2\u7ed3\u679c\u4f1a\u4e3a\u7a7a\u3002\u3010\u662f\u5426\u53ef\u4ee5\u5229\u7528\u8fd9\u4e2a\u6765\u731c\u6d4b\u8bb0\u5f55\u6570？\u3011<\/li>\n
- \u4f8b\u5982，\u5982\u679c\u8868\u4e2d\u53ea\u6709 7 \u6761\u8bb0\u5f55，\u6267\u884c LIMIT 9, 3 \u4f1a\u8fd4\u56de\u7a7a\u7ed3\u679c\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\u2171. \u5206\u9875\u516c\u5f0f<\/h6>\n
\u5982\u679c\u4f60\u5e0c\u671b\u52a8\u6001\u8ba1\u7b97\u6bcf\u9875\u7684\u8d77\u59cb\u4f4d\u7f6e，\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u516c\u5f0f：<\/p>\n
\u8d77\u59cb\u4f4d\u7f6e = (\u5f53\u524d\u9875\u7801 – 1) * \u6bcf\u9875\u8bb0\u5f55\u6570<\/p>\n
\u5982\u679c\u6bcf\u9875\u663e\u793a 3 \u6761\u8bb0\u5f55：
\n\u7b2c 1 \u9875：(1 – 1) * 3 = 0 \u2192 LIMIT 0, 3
\n\u7b2c 2 \u9875：(2 – 1) * 3 = 3 \u2192 LIMIT 3, 3
\n\u7b2c 3 \u9875：(3 – 1) * 3 = 6 \u2192 LIMIT 6, 3<\/p>\n\u4f7f\u7528\u683c\u5f0f limit m,n<\/p>\n
\u4f8b\u5982limit 0,1\u8868\u793a\u4ece\u7b2c\u4e00\u6761\u8bb0\u5f55\u5f00\u59cb，\u53d6\u4e00\u6761\u8bb0\u5f55，<\/p>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063246-6974678e8a462.png\")
<\/p>\n6. where\u6761\u4ef6\u7528\u6cd5<\/h5>\n
where\u7528\u4e8e\u6307\u5b9a\u67e5\u8be2\u6761\u4ef6<\/p>\n
select user,host from mysql.user where user = 'root';<\/p>\n
\u8981\u67e5\u8be2\u7684\u5b57\u6bb5\u540d \u5e93\u540d\u548c\u8868\u540d \u5df2\u77e5\u6761\u4ef6\u7684\u5b57\u6bb5\u540d=\u2018\u5df2\u77e5\u6761\u4ef6\u7684\u503c\u2019<\/p>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063246-6974678ef13fb.png\")
<\/p>\n7. ORDER BY\u6392\u5e8f\u67e5\u8be2<\/h5>\n
\u7528\u4e8e\u5bf9\u67e5\u8be2\u7ed3\u679c\u8fdb\u884c\u6392\u5e8f\u7684\u5173\u952e\u5b57，\u53ef\u4ee5\u6309\u4e00\u4e2a\u6216\u591a\u4e2a\u5217\u8fdb\u884c\u5347\u5e8f\u6216\u964d\u5e8f\u6392\u5217\u3002<\/p>\n
- \n
- \n
- \n
- \u9ed8\u8ba4\u6309\u5347\u5e8f(ASC)\u6392\u5e8f，\u964d\u5e8f\u9700\u8981\u6307\u5b9aDESC<\/li>\n
- \u53ef\u4ee5\u6309\u4e00\u4e2a\u6216\u591a\u4e2a\u5217\u6392\u5e8f<\/li>\n
- \u6392\u5e8f\u5217\u53ef\u4ee5\u662f\u8868\u4e2d\u7684\u5b9e\u9645\u5217，\u4e5f\u53ef\u4ee5\u662fselect\u8bed\u53e5\u4e2d\u7684\u522b\u540d<\/li>\n
- \u652f\u6301\u6570\u5b57\u3001\u65e5\u671f\u3001\u5b57\u7b26\u4e32\u7b49\u591a\u79cd\u6570\u636e\u7c7b\u578b\u6392\u5e8f<\/li>\n
- NULL\u503c\u901a\u5e38\u6392\u5728\u6700\u540e（\u5177\u4f53\u53d6\u51b3\u4e8e\u6570\u636e\u5e93\u5b9e\u73b0）<\/li>\n
- \u591a\u5217\u6392\u5e8f\u65f6，\u4f18\u5148\u7ea7\u4ece\u5de6\u5230\u53f3<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\u8bed\u6cd5：order by \u5b50\u53e5<\/p>\n
order by \u6392\u5e8f\u5b57\u6bb51 \u6392\u5e8f\u65b9\u5f0f1 ， \u6392\u5e8f\u5b57\u6bb52 \u6392\u5e8f\u65b9\u5f0f2…<\/p>\n
\u6ce8\u610f： \u5982\u679c\u6709\u591a\u4e2a\u6392\u5e8f\u6761\u4ef6，\u5219\u5f53\u524d\u8fb9\u7684\u6761\u4ef6\u503c\u4e00\u6837\u65f6，\u624d\u4f1a\u5224\u65ad\u7b2c\u4e8c\u6761\u4ef6\u3002<\/p>\n
— \u4f8b\u5b50
\nSELECT * FROM person ORDER BY math; –\u9ed8\u8ba4\u5347\u5e8f
\nSELECT * FROM person ORDER BY math desc; –\u964d\u5e8f <\/p>\n\u683c\u5f0f <\/p>\n
SELECT \u5217\u540d1, \u5217\u540d2,…
\nFROM \u8868\u540d
\nORDER BY \u5217\u540d1 [ASC|DESC], \u5217\u540d2 [ASC|DESC] <\/p>\n– \u00a0SELECT\u00a0：\u6307\u5b9a\u8981\u67e5\u8be2\u7684\u5b57\u6bb5（\u6bd4\u5982\u201c\u59d3\u540d\u201d\u201c\u5e74\u9f84\u201d）\u3002<\/p>\n
– \u00a0FROM\u00a0：\u6307\u5b9a\u8981\u67e5\u8be2\u7684\u8868（\u6bd4\u5982\u201c\u5b66\u751f\u8868\u201d\u201c\u5458\u5de5\u8868\u201d）\u3002<\/p>\n
– \u00a0ORDER BY\u00a0：\u5bf9\u67e5\u8be2\u7ed3\u679c\u6392\u5e8f，\u540e\u9762\u8ddf\u8981\u6392\u5e8f\u7684\u5217，<\/p>\n
\u00a0ASC\u00a0 \u662f\u5347\u5e8f（\u9ed8\u8ba4，\u6bd4\u5982\u6570\u5b57\u4ece\u5c0f\u5230\u5927\u3001\u6587\u5b57\u4ece A \u5230 Z），<\/p>\n
\u00a0DESC\u00a0 \u662f\u964d\u5e8f（\u6bd4\u5982\u6570\u5b57\u4ece\u5927\u5230\u5c0f\u3001\u6587\u5b57\u4ece Z \u5230 A）\u3002<\/p>\n
\u4f8b\u5b50\u6765\u5566<\/p>\n
\u5047\u8bbe\u6211\u4eec\u6709\u4e00\u5f20 student \u8868，\u7ed3\u6784\u5982\u4e0b：
\nid name age score
\n1 \u5f20\u4e09 18 85
\n2 \u674e\u56db 19 90
\n3 \u738b\u4e94 18 80
\n\u8981\u6c42：\u5355\u5217\u964d\u5e8f（\u6309\u5206\u6570\u4ece\u9ad8\u5230\u4f4e）<\/p>\nsql SELECT name, age, score
\nFROM student
\nORDER BY score DESC;<\/p>\n\u7ed3\u679c\u4f1a\u662f：
\nname age score
\n\u674e\u56db 19 90
\n\u5f20\u4e09 18 85
\n\u738b\u4e94 18 80 <\/p>\n8. grout by \u5206\u7ec4\u67e5\u8be2<\/h5>\n
\u8bed\u6cd5：group by \u5206\u7ec4\u5b57\u6bb5;<\/p>\n
\u6ce8\u610f：\u5206\u7ec4\u4e4b\u540e\u67e5\u8be2\u7684\u5b57\u6bb5：\u5206\u7ec4\u5b57\u6bb5\u3001\u805a\u5408\u51fd\u6570<\/p>\n
— \u6309\u7167\u6027\u522b\u5206\u7ec4\u3002\u5206\u522b\u67e5\u8be2\u7537\u3001\u5973\u540c\u5b66\u7684\u5e73\u5747\u5206
\nSELECT sex , AVG(math) FROM student GROUP BY sex;<\/p>\n\/\/SELECT \u5217\u540d, \u805a\u5408\u51fd\u65701(\u5217\u540d), \u805a\u5408\u51fd\u65702(\u5217\u540d)<\/p>\n
— \u6309\u7167\u6027\u522b\u5206\u7ec4\u3002\u5206\u522b\u67e5\u8be2\u7537\u3001\u5973\u540c\u5b66\u7684\u6570\u5b66\u5e73\u5747\u5206,\u4eba\u6570
\n SELECT sex , AVG(math),COUNT(id) FROM student GROUP BY sex;<\/p>\n— \u6309\u7167\u6027\u522b\u5206\u7ec4\u3002\u5206\u522b\u67e5\u8be2\u7537\u3001\u5973\u540c\u5b66\u7684\u6570\u5b66\u5e73\u5747\u5206,\u4eba\u6570 \u8981\u6c42：\u5206\u6570\u4f4e\u4e8e70\u5206\u7684\u4eba，\u4e0d\u53c2\u4e0e\u5206\u7ec4
\nSELECT sex , AVG(math),COUNT(id) FROM student WHERE math > 70 GROUP BY sex;<\/p>\n–\u6309\u7167\u6027\u522b\u5206\u7ec4\u3002\u5206\u522b\u67e5\u8be2\u7537\u3001\u5973\u540c\u5b66\u7684\u5e73\u5747\u5206,\u4eba\u6570 \u8981\u6c42：\u5206\u6570\u4f4e\u4e8e70\u5206\u7684\u4eba，\u4e0d\u53c2\u4e0e\u5206\u7ec4,\u5206\u7ec4\u4e4b\u540e\u3002
\n –\u4eba\u6570\u8981\u5927\u4e8e2\u4e2a\u4eba
\nSELECT sex , AVG(math),COUNT(id) FROM student WHERE math > 70 GROUP BY sex
\nHAVING COUNT(id) > 2;
\nSELECT sex , AVG(math),COUNT(id) \u4eba\u6570 FROM student WHERE math > 70 GROUP BY sex
\nHAVING \u4eba\u6570 > 2;<\/p>\n\/\/AVG(math)\u5e73\u5747\u6570\u5b66\u6210\u7ee9<\/p>\n
\/\/COUNT(id)\u6bcf\u7ec4\u7684\u4eba\u6570\u3010count\u3011<\/p>\n
\/\/GROUP BY sex：\u6309\u7167\u6027\u522b（sex）\u5bf9\u7b5b\u9009\u540e\u7684\u6570\u636e\u8fdb\u884c\u5206\u7ec4\u3002<\/p>\n
\/\/ WHERE \u6761\u4ef6
\nWHERE math > 70：
\n\u7b5b\u9009\u51fa\u6570\u5b66\u5206\u6570\u5927\u4e8e 70 \u7684\u8bb0\u5f55\u3002<\/p>\n\/\/HAVING \u5206\u7ec4\u540e\u6761\u4ef6;
\nHAVING COUNT(id) > 2：
\n\u8fc7\u6ee4\u6389\u4eba\u6570\u5c0f\u4e8e\u7b49\u4e8e 2 \u7684\u5206\u7ec4\u3002<\/p>\n\/\/\u7b2c\u4e00\u53e5\u548c\u7b2c\u4e8c\u53e5\u533a\u522b：
\n \u5728 SELECT \u5b50\u53e5\u4e2d，\u7ed9 COUNT(id) \u8d77\u4e86\u4e00\u4e2a\u522b\u540d \u4eba\u6570\u3002
\n \u5728 HAVING \u5b50\u53e5\u4e2d，\u76f4\u63a5\u4f7f\u7528\u4e86\u522b\u540d \u4eba\u6570\u3002
\n\u6548\u679c：
\n\u529f\u80fd\u5b8c\u5168\u76f8\u540c，\u4f46\u66f4\u76f4\u89c2\u5730\u8868\u8fbe\u4e86\u201c\u4eba\u6570\u201d\u7684\u542b\u4e49\u3002<\/p>\n— \u67e5\u8be2\u5458\u5de5\u8868\u7684\u540d\u79f0，\u6027\u522b\u3002\u90e8\u95e8\u8868\u7684\u540d\u79f0
\nSELECT emp.name,emp.gender,dept.name FROM emp,dept WHERE emp.`dept_id` = dept.`id`;<\/p>\n\/\/\u591a\u8868\u67e5\u8be2
\n\/\/WHERE emp.dept_id = dept.id：
\n\u901a\u8fc7\u6761\u4ef6 emp.dept_id = dept.id \u5c06\u4e24\u4e2a\u8868\u5173\u8054\u8d77\u6765\u3002
\n\u8fd9\u91cc\u5047\u8bbe emp \u8868\u4e2d\u7684 dept_id \u662f\u5916\u952e，\u6307\u5411 dept \u8868\u7684\u4e3b\u952e id\u3002
\n\/\/\u5148\u88ab\u7ed3\u5408\u5173\u8054\u5f62\u6210\u4e00\u4e2a\u65b0\u7684\u8868\u683c，\u7136\u540e\u518d\u67e5\u8be2\u6240\u9700\u4fe1\u606f<\/p>\nSELECT
\n t1.name, — \u5458\u5de5\u8868\u7684\u59d3\u540d
\n t1.gender,– \u5458\u5de5\u8868\u7684\u6027\u522b
\n t2.name — \u90e8\u95e8\u8868\u7684\u540d\u79f0
\nFROM
\n emp t1,
\n dept t2
\nWHERE
\n t1.`dept_id` = t2.`id`;<\/p>\n\/\/\u4f7f\u7528\u4e86\u8868\u522b\u540d：
\nemp \u8868\u88ab\u547d\u540d\u4e3a t1\u3002
\ndept \u8868\u88ab\u547d\u540d\u4e3a t2\u3002
\n\u5728 SELECT \u548c WHERE \u5b50\u53e5\u4e2d，\u7528\u522b\u540d\u4ee3\u66ff\u4e86\u8868\u540d\u3002<\/p>\n9. \u5185\u8fde\u63a5\u67e5\u8be2：<\/h5>\n
1. \u4ece\u54ea\u4e9b\u8868\u4e2d\u67e5\u8be2\u6570\u636e<\/p>\n
2.\u6761\u4ef6\u662f\u4ec0\u4e48<\/p>\n
3. \u67e5\u8be2\u54ea\u4e9b\u5b57\u6bb5<\/p>\n
a. \u9690\u5f0f\u5185\u8fde\u63a5：\u4f7f\u7528where\u6761\u4ef6\u6d88\u9664\u65e0\u7528\u6570\u636e<\/h6>\n
SELECT \u5217\u540d1, \u5217\u540d2, …
\nFROM \u88681, \u88682
\nWHERE \u88681.\u5173\u8054\u5217 = \u88682.\u5173\u8054\u5217; <\/p>\nb. \u663e\u5f0f\u5185\u8fde\u63a5<\/h6>\n
— \u8bed\u6cd5：
\nselect \u5b57\u6bb5\u5217\u8868 from \u8868\u540d1 [inner] join \u8868\u540d2 on \u6761\u4ef6
\n— \u4f8b\u5982：
\nSELECT * FROM emp INNER JOIN dept ON emp.`dept_id` = dept.`id`;
\nSELECT * FROM emp JOIN dept ON emp.`dept_id` = dept.`id`; <\/p>\n\/\/\u8fd9\u6761 SQL \u8bed\u53e5\u4f7f\u7528\u4e86 JOIN \u64cd\u4f5c，\u7528\u4e8e\u4ece\u4e24\u4e2a\u6216\u591a\u4e2a\u8868\u4e2d\u57fa\u4e8e\u67d0\u79cd\u5173\u8054\u6761\u4ef6（ON）
\n\u63d0\u53d6\u6570\u636e\u3002
\n\/\/\u662femp\u4e0edept\u4e24\u4e2a\u8868\u540d\u7ed3\u5408
\n\/\/\u6761\u4ef6\u4e2d = \u5373\u5c06\u4e24\u8868\u683c\u7ed3\u5408 <\/p>\n\u2170. JOIN<\/h6>\n
- \n
- \u5b9a\u4e49：JOIN \u662f\u4e00\u79cd SQL \u64cd\u4f5c，\u7528\u4e8e\u6839\u636e\u67d0\u4e9b\u6761\u4ef6\u5c06\u4e24\u4e2a\u6216\u591a\u4e2a\u8868\u7684\u6570\u636e\u7ec4\u5408\u5728\u4e00\u8d77\u3002<\/li>\n
- \u4f5c\u7528：\u901a\u8fc7\u5173\u8054\u6761\u4ef6（\u5982\u5916\u952e\u5173\u7cfb），\u5c06\u5206\u6563\u5728\u591a\u4e2a\u8868\u4e2d\u7684\u76f8\u5173\u6570\u636e\u6574\u5408\u5230\u4e00\u4e2a\u7ed3\u679c\u96c6\u4e2d\u3002<\/li>\n<\/ul>\n
SELECT \u5b57\u6bb5\u5217\u8868
\nFROM \u8868\u540d1 [INNER] JOIN \u8868\u540d2
\nON \u5173\u8054\u6761\u4ef6; <\/p>\n- \n
- \u53c2\u6570\u8bf4\u660e<\/li>\n<\/ul>\n
- \u5b57\u6bb5\u5217\u8868：<\/li>\n
- \n
- \n
- \n
- \u6307\u5b9a\u8981\u67e5\u8be2\u7684\u5217，\u53ef\u4ee5\u6765\u81ea\u4efb\u610f\u4e00\u4e2a\u53c2\u4e0e JOIN \u7684\u8868\u3002<\/li>\n
- \u793a\u4f8b：t1.name, t2.department_name<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \u8868\u540d1 \u548c \u8868\u540d2：<\/li>\n
- \n
- \n
- \n
- \u53c2\u4e0e\u8fde\u63a5\u64cd\u4f5c\u7684\u4e24\u5f20\u8868\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- [INNER] JOIN：<\/li>\n
- \n
- \n
- \n
- INNER JOIN \u662f\u9ed8\u8ba4\u7684\u8fde\u63a5\u7c7b\u578b，\u4e5f\u53ef\u4ee5\u7701\u7565 INNER，\u76f4\u63a5\u5199 JOIN\u3002<\/li>\n
- \u5b83\u53ea\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u6ee1\u8db3\u5173\u8054\u6761\u4ef6\u7684\u8bb0\u5f55\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- ON \u5173\u8054\u6761\u4ef6：<\/li>\n
- \n
- \n
- \n
- \u6307\u5b9a\u5982\u4f55\u5c06\u4e24\u5f20\u8868\u7684\u6570\u636e\u5173\u8054\u8d77\u6765\u3002<\/li>\n
- \u901a\u5e38\u662f\u4e00\u4e2a\u7b49\u503c\u6761\u4ef6（\u5982 t1.dept_id = t2.id）\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\u2171. \u5916\u952e<\/h6>\n
- \n
- \u5b9a\u4e49：<\/li>\n<\/ul>\n
- \n
- \n
- \n
- \u5916\u952e\u662f\u4e00\u4e2a\u8868\u4e2d\u7684\u5b57\u6bb5（\u6216\u5b57\u6bb5\u7ec4\u5408），\u5b83\u7684\u503c\u5fc5\u987b\u51fa\u73b0\u5728\u53e6\u4e00\u4e2a\u8868\u7684\u4e3b\u952e\u6216\u552f\u4e00\u952e\u4e2d\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \u4f5c\u7528：<\/li>\n<\/ul>\n
- \n
- \n
- \n
- \u786e\u4fdd\u6570\u636e\u7684\u53c2\u7167\u5b8c\u6574\u6027（Referential Integrity）\u3002<\/li>\n
- \u5efa\u7acb\u8868\u4e4b\u95f4\u7684\u5173\u8054\u5173\u7cfb，\u4fbf\u4e8e\u591a\u8868\u67e5\u8be2\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063247-6974678f391d9.png\")
<\/p>\n- \n
- \u5728 emp \u8868\u4e2d，dept_id \u662f\u4e00\u4e2a\u5916\u952e，\u5b83\u5f15\u7528\u4e86 dept \u8868\u7684\u4e3b\u952e id\u3002<\/li>\n
- \u8fd9\u610f\u5473\u7740：<\/li>\n<\/ul>\n
- \n
- \n
- \n
- emp.dept_id \u7684\u503c\u5fc5\u987b\u5b58\u5728\u4e8e dept.id \u4e2d\u3002<\/li>\n
- \u5982\u679c dept.id \u4e2d\u6ca1\u6709\u67d0\u4e2a\u503c（\u5982 3），\u5219 emp.dept_id \u4e0d\u80fd\u63d2\u5165\u8be5\u503c\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n
10. \u5916\u8fde\u63a5\u67e5\u8be2<\/h5>\n
a. \u5de6\u5916\u8fde\u63a5 — \u67e5\u8be2\u7684\u662f\u5de6\u8868\u6240\u6709\u6570\u636e\u4ee5\u53ca\u5176\u4ea4\u96c6\u90e8\u5206\u3002<\/h6>\n
\u5de6\u8fb9\u4e3a\u4e3b\u8868<\/p>\n
LEFT JOIN \u7684\u7279\u70b9<\/p>\n
- \n
- \u4fdd\u7559\u4e3b\u8868\u7684\u6240\u6709\u8bb0\u5f55：<\/li>\n<\/ul>\n
- \n
- \n
- \n
- \u5373\u4f7f\u67d0\u4e9b\u8bb0\u5f55\u5728\u4ece\u8868\u4e2d\u6ca1\u6709\u5339\u914d\u9879，\u4e3b\u8868\u7684\u8bb0\u5f55\u4ecd\u7136\u4f1a\u88ab\u4fdd\u7559\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \u672a\u5339\u914d\u7684\u4ece\u8868\u5b57\u6bb5\u663e\u793a\u4e3a NULL：<\/li>\n<\/ul>\n
- \n
- \n
- \n
- \u5982\u679c\u67d0\u6761\u8bb0\u5f55\u5728\u4ece\u8868\u4e2d\u6ca1\u6709\u5339\u914d\u9879，\u5219\u4ece\u8868\u7684\u5b57\u6bb5\u503c\u4f1a\u663e\u793a\u4e3a NULL\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
— \u8bed\u6cd5：select \u5b57\u6bb5\u5217\u8868 from \u88681 left [outer] join \u88682 on \u6761\u4ef6；
\n— \u4f8b\u5b50：
\n— \u67e5\u8be2\u6240\u6709\u5458\u5de5\u4fe1\u606f，\u5982\u679c\u5458\u5de5\u6709\u90e8\u95e8，\u5219\u67e5\u8be2\u90e8\u95e8\u540d\u79f0，\u6ca1\u6709\u90e8\u95e8，\u5219\u4e0d\u663e\u793a
\n\u90e8\u95e8\u540d\u79f0
\nSELECT t1.*,t2.`name` FROM emp t1 LEFT JOIN dept t2 ON t1.`dept_id` = t2.`id`;<\/p>\n\/\/\u6267\u884c\u987a\u5e8f
\n（1）FROM emp t1：
\n\u6307\u5b9a\u6570\u636e\u6765\u6e90\u4e3a\u4e3b\u8868 emp，\u5e76\u4e3a\u5176\u8d77\u522b\u540d t1\u3002
\n（2）LEFT JOIN dept t2：
\n\u5c06 dept \u8868\u4f5c\u4e3a\u4ece\u8868，\u5e76\u4e3a\u5176\u8d77\u522b\u540d t2\u3002
\n\u4f7f\u7528 LEFT JOIN \u786e\u4fdd\u4e3b\u8868（emp）\u7684\u6240\u6709\u8bb0\u5f55\u90fd\u4f1a\u88ab\u4fdd\u7559\u3002
\n\/\/\u9009\u62e9\u4e3b\u8868（emp）\u7684\u6240\u6709\u5217（t1.*） <\/p>\n\u2170. \u793a\u4f8b\u573a\u666f<\/h6>\n
\u5047\u8bbe\u6211\u4eec\u6709\u4e24\u5f20\u8868：<\/p>\n
- \n
- \u5b66\u751f\u8868（students）：\u5b58\u50a8\u5b66\u751f\u7684\u57fa\u672c\u4fe1\u606f<\/li>\n
- \u6210\u7ee9\u8868（scores）：\u5b58\u50a8\u5b66\u751f\u7684\u8003\u8bd5\u6210\u7ee9<\/li>\n<\/ul>\n
\n\n
\n \n \u5b66\u751f\u8868（students）<\/p>\n<\/td>\n
<\/td>\n \n \u6210\u7ee9\u8868（scores）<\/p>\n<\/td>\n
<\/td>\n<\/tr>\n \n \n id（\u4e3b\u952e）<\/p>\n<\/td>\n
\n name<\/p>\n<\/td>\n
\n student_id（\u5916\u952e）<\/p>\n<\/td>\n
\n score<\/p>\n<\/td>\n<\/tr>\n
\n \n 1<\/p>\n<\/td>\n
\n \u5c0f\u660e<\/p>\n<\/td>\n
\n 1<\/p>\n<\/td>\n
\n 90<\/p>\n<\/td>\n<\/tr>\n
\n \n 2<\/p>\n<\/td>\n
\n \u5c0f\u7ea2<\/p>\n<\/td>\n
\n 2<\/p>\n<\/td>\n
\n 85<\/p>\n<\/td>\n<\/tr>\n
\n \n 3<\/p>\n<\/td>\n
\n \u5c0f\u521a<\/p>\n<\/td>\n
\n 4<\/p>\n<\/td>\n
\n 78<\/p>\n<\/td>\n<\/tr>\n
\n \n 4<\/p>\n<\/td>\n
\n \u5c0f\u4e3d<\/p>\n<\/td>\n
<\/td>\n <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n SQL\u8bed\u53e5：<\/p>\n
SELECT students.name, scores.score
\nFROM students
\nLEFT JOIN scores
\nON students.id = scores.student_id; <\/p>\n\u67e5\u8be2\u7ed3\u679c：<\/p>\n
\n\n
\n \n name<\/p>\n<\/td>\n
\n score<\/p>\n<\/td>\n<\/tr>\n
\n \n \u5c0f\u660e<\/p>\n<\/td>\n
\n 90<\/p>\n<\/td>\n<\/tr>\n
\n \n \u5c0f\u7ea2<\/p>\n<\/td>\n
\n 85<\/p>\n<\/td>\n<\/tr>\n
\n \n \u5c0f\u521a<\/p>\n<\/td>\n
\n NULL<\/p>\n<\/td>\n<\/tr>\n
\n \n \u5c0f\u4e3d<\/p>\n<\/td>\n
\n NULL<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u5173\u952e\u70b9：<\/p>\n
- \n
- \u5de6\u8868（students）\u7684\u6240\u67094\u6761\u8bb0\u5f55\u90fd\u88ab\u8fd4\u56de\u3002<\/li>\n
- \u53f3\u8868（scores）\u4e2d，\u53ea\u6709\u4e0e\u5de6\u8868\u5339\u914d\u7684\u8bb0\u5f55（\u5c0f\u660e\u3001\u5c0f\u7ea2）\u663e\u793a\u4e86\u6210\u7ee9，\u4e0d\u5339\u914d\u7684\u8bb0\u5f55（\u5c0f\u521a\u3001\u5c0f\u4e3d）\u663e\u793a\u4e3a NULL\u3002<\/li>\n<\/ul>\n
\u5e94\u7528\u573a\u666f：<\/p>\n
- \n
- \u7edf\u8ba1\u6240\u6709\u5b66\u751f\u7684\u6210\u7ee9\u60c5\u51b5（\u5305\u62ec\u6ca1\u6709\u6210\u7ee9\u7684\u5b66\u751f）\u3002<\/li>\n
- \u627e\u51fa\u672a\u53c2\u4e0e\u8003\u8bd5\u7684\u5b66\u751f（\u901a\u8fc7\u7b5b\u9009 score IS NULL）\u3002<\/li>\n<\/ul>\n
\u5bf9\u6bd4：\u5982\u679c\u4f7f\u7528 INNER JOIN（\u5185\u8fde\u63a5），\u5219\u53ea\u4f1a\u8fd4\u56de\u5c0f\u660e\u548c\u5c0f\u7ea2\u4e24\u6761\u8bb0\u5f55，\u56e0\u4e3a\u5185\u8fde\u63a5\u53ea\u8fd4\u56de\u4ea4\u96c6\u90e8\u5206\u3002<\/p>\n
b. \u53f3\u5916\u8fde\u63a5 — \u67e5\u8be2\u7684\u662f\u53f3\u8868\u6240\u6709\u6570\u636e\u4ee5\u53ca\u5176\u4ea4\u96c6\u90e8\u5206\u3002<\/h6>\n
\u53f3\u8fb9\u4e3a\u4e3b\u8868<\/p>\n
RIGHT JOIN \u7684\u7279\u70b9<\/p>\n
- \n
- \u4fdd\u7559\u53f3\u4fa7\u8868\u7684\u6240\u6709\u8bb0\u5f55：<\/li>\n<\/ul>\n
- \n
- \n
- \n
- \u5373\u4f7f\u67d0\u4e9b\u8bb0\u5f55\u5728\u5de6\u4fa7\u8868\u4e2d\u6ca1\u6709\u5339\u914d\u9879，\u53f3\u4fa7\u8868\u7684\u8bb0\u5f55\u4ecd\u7136\u4f1a\u88ab\u4fdd\u7559\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \u672a\u5339\u914d\u7684\u5de6\u4fa7\u8868\u5b57\u6bb5\u663e\u793a\u4e3a NULL：<\/li>\n<\/ul>\n
- \n
- \n
- \n
- \u5982\u679c\u67d0\u6761\u8bb0\u5f55\u5728\u5de6\u4fa7\u8868\u4e2d\u6ca1\u6709\u5339\u914d\u9879，\u5219\u5de6\u4fa7\u8868\u7684\u5b57\u6bb5\u503c\u4f1a\u663e\u793a\u4e3a NULL\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
— \u8bed\u6cd5：
\nselect \u5b57\u6bb5\u5217\u8868 from \u88681 right [outer] join \u88682 on \u6761\u4ef6；
\n— \u4f8b\u5b50：
\nSELECT * FROM dept t2 RIGHT JOIN emp t1 ON t1.`dept_id` = t2.`id`;<\/p>\n\/\/\u6267\u884c\u987a\u5e8f
\nFROM dept t2：
\n\u6307\u5b9a\u6570\u636e\u6765\u6e90\u4e3a dept \u8868，\u5e76\u4e3a\u5176\u8d77\u522b\u540d t2\u3002
\nRIGHT JOIN emp t1：
\n\u5c06 emp \u8868\u4f5c\u4e3a\u4e3b\u8868，\u5e76\u4e3a\u5176\u8d77\u522b\u540d t1\u3002
\n\u4f7f\u7528 RIGHT JOIN \u786e\u4fdd\u4e3b\u8868（emp）\u7684\u6240\u6709\u8bb0\u5f55\u90fd\u4f1a\u88ab\u4fdd\u7559\u3002
\n\/\/SELECT *：
\n\u9009\u62e9\u4e24\u5f20\u8868\u4e2d\u7684\u6240\u6709\u5217\u3002 <\/p>\nc. \u5185\u8fde\u63a5\u4e0e\u5916\u8fde\u63a5\u7684\u533a\u522b[\u4e00\u4e2a\u4ea4\u96c6，\u4e00\u4e2a\u5e76\u96c6]<\/h6>\n
\u2170. \u5185\u8fde\u63a5（INNER JOIN）<\/h6>\n
\u5b9a\u4e49：<\/p>\n
\u53ea\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u6ee1\u8db3\u8fde\u63a5\u6761\u4ef6\u7684\u8bb0\u5f55\u3002<\/p>\n
\u5982\u679c\u67d0\u6761\u8bb0\u5f55\u5728\u4e00\u5f20\u8868\u4e2d\u6709\u5bf9\u5e94\u7684\u6570\u636e，\u4f46\u5728\u53e6\u4e00\u5f20\u8868\u4e2d\u6ca1\u6709，\u5219\u8be5\u8bb0\u5f55\u4e0d\u4f1a\u51fa\u73b0\u5728\u7ed3\u679c\u96c6\u4e2d\u3002<\/p>\n
\u2171. \u5916\u8fde\u63a5（OUTER JOIN）<\/h6>\n
\u5b9a\u4e49：<\/p>\n
\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u6ee1\u8db3\u8fde\u63a5\u6761\u4ef6\u7684\u8bb0\u5f55，\u540c\u65f6\u8fd8\u4f1a\u4fdd\u7559\u67d0\u4e9b\u4e0d\u5339\u914d\u7684\u8bb0\u5f55\u3002<\/p>\n
\u6839\u636e\u4fdd\u7559\u54ea\u4e00\u4fa7\u7684\u4e0d\u5339\u914d\u8bb0\u5f55，\u5916\u8fde\u63a5\u5206\u4e3a\u4e09\u79cd\u7c7b\u578b：\u5de6\u5916\u8fde\u63a5\u3001\u53f3\u5916\u8fde\u63a5\u548c\u5168\u5916\u8fde\u63a5\u3002<\/p>\n
11. \u5b50\u67e5\u8be2：\u67e5\u8be2\u4e2d\u5d4c\u5957\u67e5\u8be2<\/h5>\n
— \u67e5\u8be2\u5de5\u8d44\u6700\u9ad8\u7684\u5458\u5de5\u4fe1\u606f
\n— 1 \u67e5\u8be2\u6700\u9ad8\u7684\u5de5\u8d44\u662f\u591a\u5c11 9000
\nSELECT MAX(salary) FROM emp;<\/p>\n— 2 \u67e5\u8be2\u5458\u5de5\u4fe1\u606f，\u5e76\u4e14\u5de5\u8d44\u7b49\u4e8e9000\u7684
\nSELECT * FROM emp WHERE emp.`salary` = 9000;<\/p>\n— \u4e00\u6761sql\u5c31\u5b8c\u6210\u8fd9\u4e2a\u64cd\u4f5c\u3002\u8fd9\u5c31\u662f\u5b50\u67e5\u8be2
\nSELECT * FROM emp WHERE emp.`salary` = (SELECT MAX(salary) FROM emp);<\/p>\n\u3010\u5c06\u539f\u672c\u9700\u8981\u4e24\u6b21\u5f97\u5230\u7684\u6d88\u606f，\u5408\u4e3a\u4e00\u6b21\u3011
\n\u3010\u5c31\u662f\u5c06\u7b2c\u4e00\u6761\u7684\u5185\u5bb9\u5e26\u5165\u5230\u91cc\u9762\u3011 <\/p>\na. \u5b50\u67e5\u8be2\u7684\u7ed3\u679c\u662f\u5355\u884c\u5355\u5217\u7684<\/h6>\n
\u5b50\u67e5\u8be2\u53ef\u4ee5\u4f5c\u4e3a\u6761\u4ef6，\u4f7f\u7528\u8fd0\u7b97\u7b26\u53bb\u5224\u65ad\u3002 \u8fd0\u7b97\u7b26： > >= < <= =<\/p>\n
— \u67e5\u8be2\u5458\u5de5\u5de5\u8d44\u5c0f\u4e8e\u5e73\u5747\u5de5\u8d44\u7684\u4eba
\nSELECT * FROM emp WHERE emp.salary < (SELECT AVG(salary) FROM emp); <\/p>\nb. \u5b50\u67e5\u8be2\u7684\u7ed3\u679c\u662f\u591a\u884c\u5355\u5217\u7684：<\/h6>\n
\u5b50\u67e5\u8be2\u53ef\u4ee5\u4f5c\u4e3a\u6761\u4ef6，\u4f7f\u7528\u8fd0\u7b97\u7b26in\u6765\u5224\u65ad<\/p>\n
— \u67e5\u8be2'\u8d22\u52a1\u90e8'\u548c'\u5e02\u573a\u90e8'\u6240\u6709\u7684\u5458\u5de5\u4fe1\u606f
\nSELECT id FROM dept WHERE NAME = '\u8d22\u52a1\u90e8' OR NAME = '\u5e02\u573a\u90e8';
\nSELECT * FROM emp WHERE dept_id = 3 OR dept_id = 2;<\/p>\n\/\/\u8fd9\u79cd\u65b9\u5f0f\u9700\u8981\u624b\u52a8\u67e5\u627e\u90e8\u95e8 ID（\u5982 2 \u548c 3），\u4e0d\u591f\u81ea\u52a8\u5316，\u5bb9\u6613\u51fa\u9519\u3002
\n\u5982\u679c\u90e8\u95e8\u540d\u79f0\u6216 ID \u53d1\u751f\u53d8\u5316，\u5219\u9700\u8981\u624b\u52a8\u8c03\u6574\u67e5\u8be2\u8bed\u53e5\u3002<\/p>\n— \u5b50\u67e5\u8be2
\nSELECT * FROM emp WHERE dept_id IN (SELECT id FROM dept WHERE NAME = '\u8d22\u52a1\u90e8' OR NAME = '\u5e02\u573a\u90e8');<\/p>\n\/\/\u4f7f\u7528\u5b50\u67e5\u8be2\u52a8\u6001\u83b7\u53d6\u90e8\u95e8 ID，\u65e0\u9700\u624b\u52a8\u6307\u5b9a\u3002<\/p>\n
1.\u5185\u5c42\u5b50\u67e5\u8be2（\u62ec\u53f7\u5185\u7684\u90e8\u5206）
\nSELECT id FROM dept WHERE NAME = '\u8d22\u52a1\u90e8' OR NAME = '\u5e02\u573a\u90e8'
\nSELECT id：\u4ecedept\u8868\u4e2d\u53ea\u83b7\u53d6\u90e8\u95e8\u7684id\u5b57\u6bb5（\u90e8\u95e8\u7f16\u53f7）\u3002
\nFROM dept：\u6307\u5b9a\u67e5\u8be2\u7684\u8868\u662fdept（\u90e8\u95e8\u8868）\u3002
\nWHERE NAME = '\u8d22\u52a1\u90e8' OR NAME = '\u5e02\u573a\u90e8'：\u7b5b\u9009\u6761\u4ef6\u2014\u2014\u53ea\u8fd4\u56de\u90e8\u95e8\u540d\u79f0\u4e3a\u201c\u8d22\u52a1\u90e8\u201d\u6216\u201c\u5e02\u573a\u90e8\u201d\u7684\u8bb0\u5f55\u3002
\n\u6267\u884c\u7ed3\u679c：\u8fd4\u56de\u8fd9\u4e24\u4e2a\u90e8\u95e8\u7684id\u503c（\u4f8b\u5982：\u8d22\u52a1\u90e8id=10，\u5e02\u573a\u90e8id=20）\u3002<\/p>\n2. \u5916\u5c42\u4e3b\u67e5\u8be2（\u5916\u5c42\u7684\u90e8\u5206）
\nSELECT * FROM emp WHERE dept_id IN (\u5b50\u67e5\u8be2\u7ed3\u679c)
\nSELECT *：\u4eceemp\u8868\u4e2d\u83b7\u53d6\u6240\u6709\u5b57\u6bb5（*\u4ee3\u8868\u6240\u6709\u5217）\u3002
\nFROM emp：\u6307\u5b9a\u67e5\u8be2\u7684\u8868\u662femp（\u5458\u5de5\u8868）\u3002
\nWHERE dept_id IN (…)：\u7b5b\u9009\u6761\u4ef6\u2014\u2014\u5458\u5de5\u7684dept_id（\u90e8\u95e8\u7f16\u53f7）\u5fc5\u987b\u662f\u5185\u5c42\u5b50\u67e5\u8be2\u8fd4\u56de\u7684id\u5217\u8868\u4e2d\u7684\u503c\u3002
\nIN\u5173\u952e\u5b57：\u7528\u4e8e\u5224\u65ad\u67d0\u4e2a\u503c\u662f\u5426\u5728\u4e00\u4e2a\u96c6\u5408\u4e2d（\u8fd9\u91cc\u7684\u96c6\u5408\u5c31\u662f\u5b50\u67e5\u8be2\u8fd4\u56de\u7684\u90e8\u95e8id\u5217\u8868）\u3002<\/p>\n3. \u6574\u4f53\u6267\u884c\u903b\u8f91
\n\u5148\u6267\u884c\u5185\u5c42\u5b50\u67e5\u8be2，\u5f97\u5230\u7b26\u5408\u6761\u4ef6\u7684\u90e8\u95e8id\u5217\u8868（\u5982[10,20]）\u3002
\n\u518d\u6267\u884c\u5916\u5c42\u4e3b\u67e5\u8be2，\u4ece\u5458\u5de5\u8868\u4e2d\u7b5b\u9009\u51fadept_id\u5c5e\u4e8e\u8fd9\u4e2a\u5217\u8868\u7684\u5458\u5de5\u3002
\n\u6700\u7ec8\u8fd4\u56de\u6240\u6709\u5c5e\u4e8e\u201c\u8d22\u52a1\u90e8\u201d\u6216\u201c\u5e02\u573a\u90e8\u201d\u7684\u5458\u5de5\u4fe1\u606f\u3002<\/p>\n4. \u7b49\u4ef7\u5199\u6cd5（\u7528JOIN\u5b9e\u73b0）
\n\u8fd9\u6761\u8bed\u53e5\u4e5f\u53ef\u4ee5\u7528JOIN\u91cd\u5199，\u903b\u8f91\u66f4\u76f4\u89c2：<\/p>\nSELECT emp.*
\nFROM emp
\nJOIN dept ON emp.dept_id = dept.id
\nWHERE dept.name IN ('\u8d22\u52a1\u90e8', '\u5e02\u573a\u90e8');<\/p>\n\u533a\u522b：\u5b50\u67e5\u8be2\u66f4\u9002\u5408\u7b80\u5355\u7684\u8fc7\u6ee4\u573a\u666f，JOIN\u66f4\u9002\u5408\u591a\u8868\u5173\u8054\u7684\u590d\u6742\u67e5\u8be2\u3002
\n\u603b\u7ed3：\u8fd9\u6761SQL\u901a\u8fc7\u5d4c\u5957\u5b50\u67e5\u8be2\u5b9e\u73b0\u4e86\u201c\u5148\u627e\u90e8\u95e8，\u518d\u627e\u5458\u5de5\u201d\u7684\u903b\u8f91，\u662f\u6570\u636e\u5e93\u4e2d\u5e38\u7528\u7684\u5173\u8054\u67e5\u8be2\u65b9\u5f0f\u3002 <\/p>\nc. \u5b50\u67e5\u8be2\u7684\u7ed3\u679c\u662f\u591a\u884c\u591a\u5217\u7684：<\/h6>\n
\u5b50\u67e5\u8be2\u53ef\u4ee5\u4f5c\u4e3a\u4e00\u5f20\u865a\u62df\u8868\u53c2\u4e0e\u67e5\u8be2<\/p>\n
— \u67e5\u8be2\u5458\u5de5\u5165\u804c\u65e5\u671f\u662f2011-11-11\u65e5\u4e4b\u540e\u7684\u5458\u5de5\u4fe1\u606f\u548c\u90e8\u95e8\u4fe1\u606f
\n— \u5b50\u67e5\u8be2
\nSELECT * FROM dept t1 ,(SELECT * FROM emp WHERE emp.`join_date` > '2011-11-11') t2 WHERE t1.id = t2.dept_id;<\/p>\n\u3010\u6ce8\u610f：t2：\u7ed9\u8fd9\u4e2a\u5b50\u67e5\u8be2\u7684\u7ed3\u679c\u96c6\u8d77\u4e00\u4e2a\u522b\u540d（\u4e34\u65f6\u8868\u540d），\u65b9\u4fbf\u4e3b\u67e5\u8be2\u5f15\u7528\u3002\u3011
\n\u5148\u6267\u884c\u6d3e\u751f\u8868：\u4ece\u5458\u5de5\u8868\u4e2d\u7b5b\u9009\u51fa2011\u5e7411\u670811\u65e5\u4e4b\u540e\u5165\u804c\u7684\u5458\u5de5，\u5f97\u5230\u4e34\u65f6\u8868t2\u3002
\n\u518d\u6267\u884c\u4e3b\u67e5\u8be2：\u5c06\u90e8\u95e8\u8868dept（t1）\u4e0e\u4e34\u65f6\u8868t2\u901a\u8fc7dept_id\u5173\u8054，\u8fd4\u56de\u7b26\u5408\u6761\u4ef6\u7684\u90e8\u95e8\u548c\u5458\u5de5\u4fe1\u606f\u3002<\/p>\nSELECT * FROM dept t1, t2 WHERE t1.id = t2.dept_id<\/p>\n
— \u666e\u901a\u5185\u8fde\u63a5
\nSELECT * FROM emp t1,dept t2 WHERE t1.`dept_id` = t2.`id` AND t1.`join_date` > '2011-11-11' <\/p>\n12. CREATE\u64cd\u4f5c\u5e93\u3001\u8868\u540e\u7684\u76f8\u5173\u7528\u6cd5<\/h5>\n
\u3010\u56e0\u4e3a\u672c\u4eba\u7528\u7684\u5c0f\u76ae，\u6709\u4e00\u4e9b\u53d6\u81ea\u5927\u4f6c\u5185\u5bb9\u3011<\/p>\n
a. \u64cd\u4f5c\u5e93<\/h6>\n
\u2170. \u521b\u5efa\u5e93<\/h6>\n
create dabase db1;<\/p>\n
\/\/\u201cdb1\u201d \u662f\u4f60\u4e3a\u65b0\u521b\u5efa\u7684\u6570\u636e\u5e93\u6307\u5b9a\u7684\u540d\u79f0\u3002<\/p>\n
create database test charset utf8mb4;<\/p>\n
test\u4e3a\u8868\u540d, utf8mb4\u4e3a\u5b57\u7b26\u7f16\u7801<\/p>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063247-6974678f5c802.png\")
<\/p>\n\u2171. \u521b\u5efa\u5e93\u662f\u5426\u5b58\u5728，\u4e0d\u5b58\u5728\u5219\u521b\u5efa<\/h6>\n
create database if not exists db1;<\/p>\n
\/\/\u5982\u679c\u4e0d\u5b58\u5728db1\u5219\u521b\u5efa\u6570\u636e\u5e93<\/p>\n
\u2172. \u67e5\u770b\u6240\u6709\u6570\u636e\u5e93<\/h6>\n
show databases;<\/p>\n
\u2173. \u67e5\u770b\u67d0\u4e2a\u6570\u636e\u5e93\u7684\u5b9a\u4e49\u4fe1\u606f<\/h6>\n
show create database db1; <\/p>\n
\u2174. \u4fee\u6539\u6570\u636e\u5e93\u5b57\u7b26\u4fe1\u606f<\/h6>\n
alter database db1 character set utf8; <\/p>\n
- \n
- db1\u662f\u76ee\u6807\u6570\u636e\u5e93<\/li>\n
- character set utf8 \u8fd9\u90e8\u5206\u6307\u5b9a\u4e86\u8981\u5c06\u6570\u636e\u5e93\u7684\u9ed8\u8ba4\u5b57\u7b26\u96c6\u66f4\u6539\u4e3a\u201cutf8\u201d<\/li>\n
- Character Set（\u5b57\u7b26\u96c6）\u662f\u4e00\u7ec4\u7b26\u53f7\u548c\u7f16\u7801\u89c4\u5219，\u7528\u4e8e\u5b9a\u4e49\u6570\u636e\u5e93\u5982\u4f55\u5b58\u50a8\u548c\u5904\u7406\u6587\u672c\u6570\u636e<\/li>\n
- utf8 \u662f\u4e00\u79cd\u5e38\u89c1\u7684\u5b57\u7b26\u96c6，\u652f\u6301\u591a\u8bed\u8a00\u5b57\u7b26（\u5982\u4e2d\u6587\u3001\u82f1\u6587\u3001\u65e5\u6587\u7b49）， \u5e7f\u6cdb\u7528\u4e8e\u73b0\u4ee3\u6570\u636e\u5e93\u4e2d\u3002<\/li>\n
- \u4e3a\u4ec0\u4e48\u8981\u7528\u8fd9\u6761\u8bed\u53e5？<\/li>\n<\/ul>\n
- \n
- \n
- \n
- \n
- \n
- \u89e3\u51b3\u5b57\u7b26\u7f16\u7801\u95ee\u9898<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\u5982\u679c\u6570\u636e\u5e93\u7684\u9ed8\u8ba4\u5b57\u7b26\u96c6\u4e0d\u652f\u6301\u67d0\u4e9b\u8bed\u8a00（\u4f8b\u5982\u4e2d\u6587），\u53ef\u80fd\u4f1a\u5bfc\u81f4\u4e71\u7801\u95ee\u9898\u3002\u901a\u8fc7\u5c06\u5b57\u7b26\u96c6\u8bbe\u7f6e\u4e3a\u201cutf8\u201d，\u53ef\u4ee5\u786e\u4fdd\u6570\u636e\u5e93\u80fd\u591f\u6b63\u786e\u5b58\u50a8\u548c\u663e\u793a\u591a\u8bed\u8a00\u6587\u672c\u3002<\/p>\n
- \n
- \n
- \n
- \n
- \n
- \u7edf\u4e00\u5b57\u7b26\u96c6<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\u5728\u5f00\u53d1\u8fc7\u7a0b\u4e2d，\u4e3a\u4e86\u4fdd\u8bc1\u6570\u636e\u4e00\u81f4\u6027，\u901a\u5e38\u4f1a\u5c06\u6240\u6709\u6570\u636e\u5e93\u548c\u8868\u7684\u5b57\u7b26\u96c6\u7edf\u4e00\u8bbe\u7f6e\u4e3a\u201cutf8\u201d\u3002<\/p>\n
\u2175. \u5220\u9664\u6570\u636e\u5e93<\/h6>\n
drop database db1;<\/p>\n
\u00a0<\/p>\n
b. \u64cd\u4f5c\u8868<\/h6>\n
\u2170. \u521b\u5efa\u8868<\/h6>\n
\u4f7f\u7528\u521a\u521a\u521b\u5efa\u7684\u6570\u636e\u5e93use test \u521b\u5efa\u4e00\u4e2a\u8868create table t1(id INT);<\/p>\n
t1\u4e3a\u8868\u540d, id\u4e3a\u5b57\u6bb5, INT\u4e3a\u5b57\u6bb5\u7c7b\u578b<\/p>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063247-6974678f7408c.png\")
<\/p>\ncreate table student(
\n id int,
\n name varchar(32),
\n age int ,
\n score double(4,1),
\n birthday date,
\n insert_time timestamp
\n );<\/p>\n\u5206\u6790
\n\/\/int\u5728\u53d8\u91cf\u540e\u9762，
\n \u5982id int，\u542b\u4e49：\u5b9a\u4e49\u4e86\u4e00\u4e2a\u540d\u4e3aid\u7684\u5b57\u6bb5，\u6570\u636e\u7c7b\u578b\u4e3aINT\u3002 <\/p>\n\/\/VARCHAR \u662f\u4e00\u79cd\u53ef\u53d8\u957f\u5ea6\u7684\u5b57\u7b26\u4e32\u7c7b\u578b\u3002
\n\/\/(32) \u8868\u793a\u8be5\u5b57\u6bb5\u6700\u591a\u53ef\u4ee5\u5b58\u50a832\u4e2a\u5b57\u7b26\u3002
\n \u5982\u679c\u5b9e\u9645\u5b58\u50a8\u7684\u5b57\u7b26\u5c11\u4e8e32\u4e2a，\u53ea\u4f1a\u5360\u7528\u5b9e\u9645\u9700\u8981\u7684\u7a7a\u95f4\u3002<\/p>\n\/\/DOUBLE \u662f\u4e00\u79cd\u6d6e\u70b9\u6570\u7c7b\u578b，\u7528\u4e8e\u5b58\u50a8\u5c0f\u6570\u3002
\n\/\/(4,1) \u8868\u793a\u603b\u5171\u53ef\u4ee5\u5b58\u50a84\u4f4d\u6570\u5b57，\u5176\u4e2d1\u4f4d\u662f\u5c0f\u6570\u90e8\u5206\u3002
\n \u4f8b\u5982：\u53ef\u4ee5\u5b58\u50a8\u7684\u503c\u5305\u62ec 99.9\u300110.5 \u7b49\u3002
\n \u8d85\u51fa\u8303\u56f4\u7684\u503c（\u5982 100.5 \u6216 999.9）\u4f1a\u5bfc\u81f4\u9519\u8bef\u3002\u3010\u5305\u62ec\u5c0f\u6570\u70b9\u3011<\/p>\n\/\/birthday DATE，，\u5b9a\u4e49\u4e86\u4e00\u4e2a\u540d\u4e3abirthday\u7684\u5b57\u6bb5，\u6570\u636e\u7c7b\u578b\u4e3aDATE\u3002
\n\/\/DATE \u7c7b\u578b\u4e13\u95e8\u7528\u4e8e\u5b58\u50a8\u65e5\u671f，\u683c\u5f0f\u4e3a YYYY-MM-DD\u3002<\/p>\n\/\/TIMESTAMP \u7c7b\u578b\u7528\u4e8e\u5b58\u50a8\u65e5\u671f\u548c\u65f6\u95f4，\u683c\u5f0f\u4e3a YYYY-MM-DD HH:MM:SS\u3002
\n \u5b83\u4f1a\u81ea\u52a8\u8bb0\u5f55\u5f53\u524d\u7684\u65e5\u671f\u548c\u65f6\u95f4（\u5982\u679c\u672a\u6307\u5b9a\u503c）\u3002<\/p>\n\u603b\u7ed3
\n \u8fd9\u6761\u8bed\u53e5\u521b\u5efa\u4e86\u4e00\u4e2a\u540d\u4e3astudent\u7684\u8868，\u5305\u542b\u4ee5\u4e0b\u5b57\u6bb5：
\n id：\u5b66\u751f\u7684\u552f\u4e00\u6807\u8bc6\u7b26（\u6574\u6570）\u3002
\n name：\u5b66\u751f\u7684\u59d3\u540d（\u6700\u591a32\u4e2a\u5b57\u7b26\u7684\u5b57\u7b26\u4e32）\u3002
\n age：\u5b66\u751f\u7684\u5e74\u9f84（\u6574\u6570）\u3002
\n score：\u5b66\u751f\u7684\u5206\u6570（\u6700\u591a4\u4f4d\u6570\u5b57，\u5176\u4e2d1\u4f4d\u662f\u5c0f\u6570）\u3002
\n birthday：\u5b66\u751f\u7684\u751f\u65e5（\u65e5\u671f）\u3002
\n insert_time：\u8bb0\u5f55\u6570\u636e\u63d2\u5165\u7684\u65f6\u95f4（\u65f6\u95f4\u6233）\u3002<\/p>\n\u989d\u5916
\n \/\/id\u5b57\u6bb5\u4f1a\u88ab\u8bbe\u7f6e\u4e3a\u4e3b\u952e（Primary Key），\u4ee5\u786e\u4fdd\u6bcf\u6761\u8bb0\u5f55\u7684\u552f\u4e00\u6027\u3002
\n id INT PRIMARY KEY<\/p>\n\/\/\u5982\u679c\u5e0c\u671binsert_time\u5b57\u6bb5\u81ea\u52a8\u8bb0\u5f55\u63d2\u5165\u65f6\u95f4，\u53ef\u4ee5\u6dfb\u52a0\u9ed8\u8ba4\u503c
\n insert_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP
\n （default current_timestamp） <\/p>\n\u2171. \u67e5\u770b\u8868\u7ed3\u6784<\/h6>\n
desc \u8868\u540d;<\/p>\n
\u5982：desc t1;<\/p>\n
\n
\u5f53\u4f60\u6267\u884c\u8fd9\u6761\u547d\u4ee4\u65f6，\u6570\u636e\u5e93\u4f1a\u8fd4\u56de\u8be5\u8868\u7684\u8be6\u7ec6\u7ed3\u6784\u4fe1\u606f，<\/p>\n
\u5305\u62ec\u4ee5\u4e0b\u5185\u5bb9：<\/p>\n
- \n
- \u5b57\u6bb5\u540d\u79f0 (Field)：\u8868\u4e2d\u6bcf\u4e00\u5217\u7684\u540d\u5b57\u3002<\/li>\n
- \u6570\u636e\u7c7b\u578b (Type)：\u6bcf\u4e2a\u5b57\u6bb5\u7684\u6570\u636e\u7c7b\u578b（\u5982 INT\u3001VARCHAR\u3001DATE \u7b49）\u3002<\/li>\n
- \u662f\u5426\u5141\u8bb8 NULL \u503c (Null)：\u8be5\u5b57\u6bb5\u662f\u5426\u53ef\u4ee5\u5b58\u50a8 NULL \u503c\u3002<\/li>\n
- \u4e3b\u952e\u6807\u8bc6 (Key)：\u5982\u679c\u67d0\u4e2a\u5b57\u6bb5\u662f\u4e3b\u952e（Primary Key），\u8fd9\u91cc\u4f1a\u663e\u793a PRI\u3002<\/li>\n
- \u9ed8\u8ba4\u503c (Default)：\u5b57\u6bb5\u7684\u9ed8\u8ba4\u503c（\u5982\u679c\u6709）\u3002<\/li>\n
- \u989d\u5916\u4fe1\u606f (Extra)：\u4f8b\u5982\u81ea\u589e\u5b57\u6bb5（AUTO_INCREMENT）\u7b49\u9644\u52a0\u5c5e\u6027\u3002<\/li>\n<\/ul>\n
\n\n
\n \n Field<\/p>\n<\/td>\n
\n Type<\/p>\n<\/td>\n
\n Null<\/p>\n<\/td>\n
\n Key<\/p>\n<\/td>\n
\n Default<\/p>\n<\/td>\n
\n Extra<\/p>\n<\/td>\n<\/tr>\n
\n \n id<\/p>\n<\/td>\n
\n int(11)<\/p>\n<\/td>\n
\n NO<\/p>\n<\/td>\n
\n PRI<\/p>\n<\/td>\n
\n NULL<\/p>\n<\/td>\n
\n auto_increment<\/p>\n<\/td>\n<\/tr>\n
\n \n name<\/p>\n<\/td>\n
\n varchar(50)<\/p>\n<\/td>\n
\n YES<\/p>\n<\/td>\n
<\/td>\n \n NULL<\/p>\n<\/td>\n
<\/td>\n<\/tr>\n \n \n age<\/p>\n<\/td>\n
\n int(11)<\/p>\n<\/td>\n
\n YES<\/p>\n<\/td>\n
<\/td>\n \n NULL<\/p>\n<\/td>\n
\n \n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u2172. \u4fee\u6539\u8868\u540d<\/h6>\n
alter table \u8868\u540d rename to \u65b0\u7684\u8868\u540d;<\/p>\n
\u2173. \u67e5\u770b\u521b\u5efa\u8868\u7684SQL\u8bed\u53e5<\/h6>\n
show create table \u8868\u540d;<\/p>\n
\u2174. \u6dfb\u52a0\u5b57\u6bb5\u3010\u6dfb\u52a0\u4e00\u5217\u3011<\/h6>\n
alter table \u8868\u540d add \u5217\u540d \u6570\u636e\u7c7b\u578b;<\/p>\n
\u5982：alter table t1 add name varchar(32);<\/p>\n
t1\u4e3a\u8981\u4fee\u6539\u7684\u8868\u540d, name\u4e3a\u589e\u52a0\u7684\u5b57\u6bb5\u540d, varchar(32)\u662f\u5b57\u6bb5\u7c7b\u578b<\/p>\n
\u2175. \u5220\u9664\u5217<\/h6>\n
alter table \u8868\u540d drop \u5217\u540d;<\/p>\n
\u2176. \u63d2\u5165\u6570\u636e<\/h6>\n
insert into t1 value (1,"aa"),(2,"bb"),(3,"cc");<\/p>\n
\u2177. \u5220\u9664\u8868<\/h6>\n
drop table \u8868\u540d;<\/p>\n
drop table if exists \u8868\u540d ;<\/p>\n
\u5982：drop table t1;<\/p>\n
\u6267\u884c\u5b8c\u4e4b\u540e，\u518d\u6b21show table\u6b64\u65f6\u5219\u65e0\u5185\u5bb9<\/p>\n
\u3010drop\u662f\u5220\u9664,add\u662f\u6dfb\u52a0\u3011<\/p>\n
\u2178. \u591a\u6761\u4ef6\u67e5\u8be2\u2014and<\/h6>\n
\u4e3a\u4e86\u65b9\u4fbf\u6f14\u793a，<\/p>\n
\u5728\u6570\u636e\u5e93test\u4e2d\u518d\u63d2\u5165\u4e00\u6761name\u4e3aaa\u7684\u6570\u636e<\/p>\n
insert into t1 value (4,"aa") \u7136\u540e\u67e5\u8be2name\u4e3aaa,id\u4e3a1\u7684\u6570\u636e<\/p>\n
select * from test.t1 where name = "aa" and id =1;<\/p>\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063247-6974678f8e3a0.png\")
<\/p>\nX. \u591a\u6761\u4ef6\u67e5\u8be2\u2014or（\u91cd\u8981！！！）<\/h6>\n
and\u662f\u5fc5\u987b\u4e24\u4e2a\u6761\u4ef6\u90fd\u6210\u7acb，<\/p>\n
or\u662f\u524d\u540e\u6210\u7acb\u4e00\u4e2a\u6761\u4ef6\u5373\u53ef，\u5728sql\u6ce8\u5165\u91cc\u7ecf\u5e38\u4f7f\u7528or 1=1，\u56e0\u4e3a1=1\u8fd9\u4e2a\u6761\u4ef6\u5fc5\u7136\u6210\u7acb，\u5c31\u4e0d\u7528\u5173\u5176\u4ed6\u6761\u4ef6\u662f\u4ec0\u4e48\u4e86<\/p>\n
\u3010\u653b\u51fb\u8005\u53ef\u4ee5\u901a\u8fc7\u8fd9\u79cd\u65b9\u5f0f\u5f97\u4ee5\u4fb5\u5165\u8bbf\u95ee\u6240\u6709\u6570\u636e\u3011<\/p>\n
select * from test.t1 where name = "aa" or 1=1;<\/p>\n
\u56e0\u4e3a1=1\u5fc5\u7136\u6210\u7acb，\u67e5\u8be2\u8bed\u53e5\u4f1a\u76f4\u63a5\u5ffd\u7565name=\u201caa\u201d，\u56e0\u6b64\u5e76\u6ca1\u6709\u67e5\u8be2name\u4e3aaa\u7684\u6570\u636e，\u800c\u662f\u67e5\u8be2\u4e86\u6240\u6709\u7684\u6570\u636e\u3002<\/p>\n
X\u2170. \u8054\u5408\u67e5\u8be2\u2014union（\u91cd\u8981！！！）<\/h6>\n
union\u53ef\u7528\u4e8e\u5c06\u4e24\u4e2asql\u8bed\u53e5\u8054\u5408\u8d77\u6765，\u628a\u7ed3\u679c\u5408\u5e76\u5728\u4e00\u4e2a\u7ed3\u679c\u96c6\u91cc \u793a\u4f8b：select * from test.t1 union select 1,2;<\/p>\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063247-6974678fe9699.png\")
<\/p>\n- \n
- \n
- \n
- \u524d\u534a\u90e8\u5206select* from test.t1\u67e5\u8be2\u4e86t1\u8868\u7684\u5168\u90e8\u6570\u636e\u3010\u5728 SQL \u4e2d，\u00a0*\u00a0 \u662f\u901a\u914d\u7b26，\u4ee3\u8868\u201c\u6240\u6709\u5b57\u6bb5\u201d\u3002\u3011<\/li>\n
- \u540e\u534a\u90e8\u5206select 1,2\u53ef\u4ee5\u7528\u4e8e\u6d4b\u8bd5\u8be5\u8868\u4e2d\u6709\u591a\u5c11\u4e2a\u5b57\u6bb5，\u5177\u4f53\u7528\u6cd5\u5982\u4e0b：<\/li>\n
- \u4f8b\u5982：\u5047\u8bbetest.t1\u8868\u6709\u4e24\u4e2a\u5b57\u6bb5<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \n
- \n
- \n
- \n
- \u4f7f\u7528select * from test.t1 union select 1;\u4f1a\u62a5\u9519，\u56e0\u4e3aselect 1\u7684\u5b57\u6bb5\u53ea\u67091\u4e2a<\/li>\n
- \u800cselect * from test.t1\u7684\u5b57\u6bb5\u6709\u4e24\u4e2a\u3010\u5c31\u662f\u6709\u4e24\u5217\u3011，\u5b57\u6bb5\u4e2a\u6570\u4e0d\u5339\u914d\u56e0\u6b64\u4f1a\u62a5\u9519\u3002\u53ef\u4ee5\u901a\u8fc7\u8fd9\u79cd\u62a5\u9519\u8fdb\u884c\u5b57\u6bb5\u6570\u91cf\u7684\u63a2\u6d4b，\u5b57\u6bb5\u6570\u91cf\u4e0d\u4e00\u81f4\u4f1a\u62a5\u9519，\u5b57\u6bb5\u6570\u91cf\u4e00\u81f4\u5219\u4e0d\u4f1a\u62a5\u9519\u3002<\/li>\n
- \u589e\u52a0\u5b57\u6bb5\u8fdb\u884c\u63a2\u6d4b，\u4f7f\u7528select * from test.t1 union select 1,2;\u63a2\u6d4b\u6210\u529f，\u8be5t1\u8868\u7684\u5b57\u6bb5\u66b4\u9732<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063248-697467901e279.png\")
<\/p>\n\u3010\u5c31\u662f，\u53ef\u4ee5\u7528\u6765\u63a2\u6d4b\u5b57\u6bb5\u6570\u91cf，1，2，3，4，\u4e00\u4e2a\u4e2a\u8bd5\u51fa\u6765，\u5c31\u53ef\u4ee5\u77e5\u9053\u76ee\u6807\u6709\u591a\u5c11\u4e2a\u5217\u3011<\/p>\n
- \n
- \n
- \n
- \u5173\u952e\u89c4\u5219<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
– \u5b57\u6bb5\u6570\u91cf\u4e00\u81f4：\u4e24\u4e2a \u00a0SELECT\u00a0 \u8bed\u53e5\u7684\u5b57\u6bb5\u6570\u91cf\u5fc5\u987b\u76f8\u540c，\u5426\u5219\u4f1a\u62a5\u9519（\u5982\u793a\u4f8b\u4e2d\u201c\u00a0select * from test.t1 union select 1;\u00a0 \u62a5\u9519，\u56e0\u4e3a\u5b57\u6bb5\u6570\u4e0d\u5339\u914d\u201d）\u3002<\/p>\n
– \u6570\u636e\u7c7b\u578b\u517c\u5bb9（\u5373\u76f8\u540c\u6216\u53ef\u8f6c\u6362）：\u5bf9\u5e94\u4f4d\u7f6e\u7684\u5b57\u6bb5\u6570\u636e\u7c7b\u578b\u9700\u53ef\u517c\u5bb9（\u5982\u7b2c\u4e00\u4e2a\u67e5\u8be2\u7684\u7b2c 1 \u5217\u662f\u5b57\u7b26\u4e32，\u7b2c\u4e8c\u4e2a\u67e5\u8be2\u7684\u7b2c 1 \u5217\u4e5f\u9700\u662f\u5b57\u7b26\u4e32\u6216\u53ef\u8f6c\u6362\u7684\u7c7b\u578b）\u3002<\/p>\n
– \u53bb\u91cd\u9ed8\u8ba4\u89c4\u5219：\u00a0UNION\u00a0 \u4f1a\u81ea\u52a8\u53bb\u9664\u7ed3\u679c\u96c6\u4e2d\u7684\u91cd\u590d\u884c；\u82e5\u9700\u4fdd\u7559\u91cd\u590d\u884c，\u9700\u7528 \u00a0UNION ALL\u00a0\u3002<\/p>\n
\u4e3e\u4e2a\u4f8b\u5b50：
\n – \u7b2c\u4e00\u4e2a\u67e5\u8be2\u7ed3\u679c\u662f [1, 2, 3] – \u7b2c\u4e8c\u4e2a\u67e5\u8be2\u7ed3\u679c\u662f [3, 4, 5]
\n – \u7528 UNION \u5408\u5e76\u540e，\u7ed3\u679c\u4f1a\u662f [1, 2, 3, 4, 5] （\u81ea\u52a8\u53bb\u6389\u4e86\u91cd\u590d\u7684 3 ）
\n\u5982\u679c\u60f3\u8981\u4fdd\u7559\u91cd\u590d\u884c，\u5c31\u9700\u8981\u4f7f\u7528 UNION ALL ，\u6b64\u65f6\u5408\u5e76\u540e\u7684\u7ed3\u679c\u4f1a\u662f [1, 2, 3, 3, 4, 5] \u3002 <\/p>\n13. \u7279\u6b8a\u8868\u7684\u4f7f\u7528<\/h5>\n
\u2170. information_schema.SCHEMATA\u8868<\/h6>\n
\u5148\u770b\u4e0binformation_schema.SCHEMATA\u8868\u91cc\u6709\u54ea\u4e9b\u5b57\u6bb5: select * from information_schema.SCHEMATA;<\/p>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063248-69746790b3058.png\")
<\/p>\n\u53ef\u4ee5\u53d1\u73b0show databases;\u7b49\u4ef7\u4e8eselect SCHEMA_NAME from information_schema.SCHEMATA;<\/p>\n
\u2171. information_schema.TABLES\u8868<\/h6>\n
\u5148\u770b\u4e0binformation_schema.SCHEMATA\u8868\u91cc\u6709\u54ea\u4e9b\u5b57\u6bb5: select * from information_schema.TABLES;<\/p>\n
\n
![\"\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063249-697467916bff0.png\")
<\/p>\n\u2172. \u67e5\u770b\u6307\u5b9a\u6570\u636e\u5e93\u7684\u8868\u4fe1\u606f\u3010TABLES\u3011<\/h6>\n
select * from information_schema.TABLES where table_schema = "test";<\/p>\n
\n
![\"\"](\"2026-01-24x2uygfe3ypm.png\")
<\/p>\n\u2173. \u67e5\u770b\u6307\u5b9a\u6570\u636e\u5e93\u7684\u5217\u4fe1\u606f\u3010COLUMNS\u3011<\/h6>\n
select * from information_schema.COLUMNS where table_schema = "test";<\/p>\n
14. \u6ce8\u91ca\u7b26<\/h5>\n
\u6ce8\u91ca\u662f\u4ee3\u7801\u4e2d\u7528\u6765\u201c\u89e3\u91ca\u903b\u8f91\u201d\u4f46\u4e0d\u4f1a\u88ab\u7a0b\u5e8f\u6267\u884c\u7684\u5185\u5bb9<\/p>\n
\u5728MySQL\u4e2d，\u5e38\u89c1\u6ce8\u91ca\u7b26\u7684\u8868\u8fbe\u65b9\u5f0f：#\u6216–\u7a7a\u683c\u6216\/**\/，<\/p>\n
\u7279\u6b8a\u7f16\u7801（URL\u7f16\u7801）\u4e00\u822c\u4f7f\u7528\u7b2c\u4e8c\u79cd \u6ce8：%23\u5c31\u76f8\u5f53\u4e8e# ,%20\u76f8\u5f53\u4e8e\u7a7a\u683c，%27\u76f8\u5f53\u4e8e\u5f15\u53f7\u3002<\/p>\n
- \n
- \n
- \n
- #\u00a0：\u5355\u884c\u6ce8\u91ca，\u4ece\u00a0#\u00a0\u5f00\u59cb\u5230\u884c\u5c3e\u7684\u5185\u5bb9\u90fd\u4f1a\u88ab\u89c6\u4e3a\u6ce8\u91ca\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\/\/\u793a\u4f8b：\u00a0SELECT * FROM student # \u67e5\u8be2\u6240\u6709\u5b66\u751f\u6570\u636e\u00a0<\/p>\n
- \n
- \n
- \n
- — \u7a7a\u683c\u00a0（\u6ce8\u610f\u00a0—\u00a0\u540e\u5fc5\u987b\u8ddf\u7a7a\u683c）：\u4e5f\u662f\u5355\u884c\u6ce8\u91ca，\u4ece\u00a0— \u7a7a\u683c\u00a0\u5f00\u59cb\u5230\u884c\u5c3e\u751f\u6548\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\/\/\u793a\u4f8b：\u00a0SELECT name FROM student — \u53ea\u67e5\u5b66\u751f\u59d3\u540d<\/p>\n
- \n
- \n
- \n
- \u00a0\/* *\/\u00a0：\u591a\u884c\u6ce8\u91ca，\u00a0\/*\u00a0\u548c\u00a0*\/\u00a0\u4e4b\u95f4\u7684\u6240\u6709\u5185\u5bb9\u90fd\u4f1a\u88ab\u6ce8\u91ca（\u53ef\u4ee5\u8de8\u591a\u884c）\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\/\/\u793a\u4f8b：<\/p>\n
\/*
\n\u8fd9\u662f\u4e00\u4e2a\u591a\u884c\u6ce8\u91ca
\n\u7528\u6765\u89e3\u91ca\u4e0b\u9762\u7684\u67e5\u8be2\u903b\u8f91：\u67e5\u8be2\u5e74\u9f84\u5927\u4e8e18\u7684\u5b66\u751f\u59d3\u540d\u548c\u5206\u6570
\n*\/
\nSELECT name, score FROM student WHERE age > 18;<\/p>\n\u5185\u5d4c\u6ce8\u91ca（\u8865）<\/h6>\n
\u5f62\u5f0f：\/*!code*\/<\/p>\n
\u5b83\u770b\u4f3c\u662f\u6ce8\u91ca，\u4f46MySQL\u4f1a\u6267\u884c\u00a0\/*!…*\/\u00a0\u5185\u90e8\u7684SQL\u8bed\u53e5，\u5e38\u7528\u4e8e\u5b9e\u73b0SQL\u8bed\u6cd5\u7684\u517c\u5bb9\u6027\u6216\u7279\u6b8a\u6267\u884c\u903b\u8f91（\u6bd4\u5982SQL\u6ce8\u5165\u573a\u666f\u4e2d\u7684\u8bed\u53e5\u6784\u9020）\u3002<\/p>\n
\u5982\u679c\u6ca1\u6709 \u00a0\/*! *\/\u00a0 \u8fd9\u79cd\u5185\u5d4c\u6ce8\u91ca\u683c\u5f0f，\u5355\u7eaf\u7684 \u00a0\/* *\/\u00a0 \u6ce8\u91ca\u91cc\u7684\u5185\u5bb9\u4f1a\u88abMySQL\u5b8c\u5168\u5ffd\u7565，\u4e0d\u4f1a\u6267\u884c\u3002<\/p>\n
\u5185\u8054\u6ce8\u91ca\u53ef\u4ee5\u7528\u4e8e\u6574\u4e2asql\u8bed\u53e5\u4e2d，\u7528\u6765\u6267\u884cSQL\u8bed\u53e5<\/p>\n
-1 \/*!union*\/ \/*!select*\/ 1,2,3<\/p>\n
\u8fd9\u91cc\u7684\u00a0\/*!union*\/\u00a0\u548c\u00a0\/*!select*\/\u00a0\u4f1a\u88abMySQL\u5f53\u4f5c\u6709\u6548SQL\u6267\u884c，\u5b9e\u9645\u7b49\u6548\u4e8e\u00a0-1 union select 1,2,3\u00a0，<\/p>\n
\u5e38\u7528\u4e8e\u6570\u636e\u5e93\u7684SQL\u6ce8\u5165\u6d4b\u8bd5\u6216\u653b\u51fb\u573a\u666f，\u901a\u8fc7\u8fd9\u79cd\u201c\u4f2a\u88c5\u201d\u7684\u6ce8\u91ca\u5f62\u5f0f\u6765\u7ed5\u8fc7\u67d0\u4e9b\u8fc7\u6ee4\u89c4\u5219\u3002<\/p>\n
15. \u589e\u52a0，\u5220\u9664，\u4fee\u6539<\/h5>\n
\u2170. \u589e\u52a0 insert into<\/h6>\n
— \u5199\u5168\u6240\u6709\u5217\u540d
\ninsert into \u8868\u540d(\u5217\u540d1,\u5217\u540d2,…\u5217\u540dn) values(\u503c1,\u503c2,…\u503cn);<\/p>\n— \u4e0d\u5199\u5217\u540d（\u6240\u6709\u5217\u5168\u90e8\u6dfb\u52a0）
\ninsert into \u8868\u540d values(\u503c1,\u503c2,…\u503cn);<\/p>\n— \u63d2\u5165\u90e8\u5206\u6570\u636e
\ninsert into \u8868\u540d(\u5217\u540d1,\u5217\u540d2) values(\u503c1,\u503c2);<\/p>\n\/\/\u8868\u540d：\u8981\u63d2\u5165\u6570\u636e\u7684\u76ee\u6807\u8868\u3002
\n \u5217\u540d：\u6307\u5b9a\u8981\u63d2\u5165\u6570\u636e\u7684\u5217（\u5b57\u6bb5）\u3002\u5982\u679c\u7701\u7565\u5217\u540d，\u5219\u9700\u8981\u4e3a\u8868\u4e2d\u7684\u6240\u6709\u5217\u63d0\u4f9b\u503c\u3002
\n \u503c：\u5bf9\u5e94\u5217\u7684\u5177\u4f53\u6570\u636e\u503c\u3002
\n\/\/INSERT \u662f\u4e00\u4e2a\u975e\u5e38\u91cd\u8981\u7684 SQL \u5173\u952e\u5b57，\u7528\u4e8e\u5411\u8868\u4e2d\u63d2\u5165\u65b0\u6570\u636e <\/p>\n\u2171. \u5220\u9664 delete<\/h6>\n
— \u5220\u9664\u8868\u4e2d\u6570\u636e
\ndelete from \u8868\u540d where \u5217\u540d = \u503c;<\/p>\n— \u5220\u9664\u8868\u4e2d\u6240\u6709\u6570\u636e
\ndelete from \u8868\u540d;<\/p>\n\/\/\u9010\u884c\u5220\u9664：DELETE \u4f1a\u9010\u884c\u626b\u63cf\u5e76\u5220\u9664\u8868\u4e2d\u7684\u6570\u636e
\n \/\/DELETE \u64cd\u4f5c\u662f\u4e8b\u52a1\u6027\u7684，\u53ef\u4ee5\u56de\u6eda（Rollback）\u3002\u5982\u679c\u5220\u9664\u8fc7\u7a0b\u4e2d\u51fa\u73b0\u95ee\u9898，
\n \u53ef\u4ee5\u901a\u8fc7\u4e8b\u52a1\u6062\u590d\u6570\u636e\u3002
\n \/\/\u6027\u80fd\u8f83\u6162<\/p>\n— \u5220\u9664\u8868\u4e2d\u6240\u6709\u6570\u636e（\u9ad8\u6548 \u5148\u5220\u9664\u8868，\u7136\u540e\u518d\u521b\u5efa\u4e00\u5f20\u4e00\u6837\u7684\u8868\u3002）
\ntruncate table \u8868\u540d;<\/p>\n\/\/\u76f4\u63a5\u6e05\u7a7a\u8868：TRUNCATE \u4e0d\u4f1a\u9010\u884c\u5220\u9664\u6570\u636e，\u800c\u662f\u76f4\u63a5\u91ca\u653e\u5b58\u50a8\u6570\u636e\u7684\u6570\u636e\u9875，
\n \u4ece\u800c\u5feb\u901f\u6e05\u7a7a\u8868\u3002
\n \/\/\u65e0\u6cd5\u6761\u4ef6\u8fc7\u6ee4：TRUNCATE \u53ea\u80fd\u6e05\u7a7a\u6574\u4e2a\u8868，\u4e0d\u80fd\u6307\u5b9a\u6761\u4ef6\u5220\u9664\u90e8\u5206\u6570\u636e<\/p>\n\u4e8c\u8005\u533a\u522b
\n\u7279\u6027DELETETRUNCATE
\n\u5220\u9664\u65b9\u5f0f\u9010\u884c\u5220\u9664\u76f4\u63a5\u91ca\u653e\u6570\u636e\u9875
\n\u662f\u5426\u652f\u6301\u6761\u4ef6\u8fc7\u6ee4\u652f\u6301（\u901a\u8fc7 WHERE \u5b50\u53e5）\u4e0d\u652f\u6301
\n\u4e8b\u52a1\u5b89\u5168\u6027\u652f\u6301\u56de\u6eda\u901a\u5e38\u4e0d\u53ef\u56de\u6eda
\n\u89e6\u53d1\u5668\u89e6\u53d1\u89e6\u53d1\u5668\u4e0d\u89e6\u53d1\u89e6\u53d1\u5668
\n\u6027\u80fd\u8f83\u6162（\u5c24\u5176\u662f\u5927\u6570\u636e\u91cf\u65f6）\u9ad8\u6548
\n\u81ea\u589e\u5217\u91cd\u7f6e\u4e0d\u91cd\u7f6e\u91cd\u7f6e
\n\u9002\u7528\u573a\u666f\u9700\u8981\u5220\u9664\u90e8\u5206\u6570\u636e\u6216\u4e8b\u52a1\u5b89\u5168\u65f6\u9700\u8981\u5feb\u901f\u6e05\u7a7a\u6574\u4e2a\u8868\u65f6<\/p>\n\u89e6\u53d1\u5668（Trigger）
\n \u662f\u6570\u636e\u5e93\u4e2d\u4e00\u79cd\u7279\u6b8a\u7684\u5b58\u50a8\u8fc7\u7a0b，\u5b83\u4e0e\u8868\u7ed1\u5b9a\u5728\u4e00\u8d77，
\n \u5f53\u8868\u53d1\u751f\u7279\u5b9a\u4e8b\u4ef6（\u5982\u63d2\u5165\u3001\u66f4\u65b0\u6216\u5220\u9664\u6570\u636e）\u65f6，\u4f1a\u81ea\u52a8\u89e6\u53d1\u6267\u884c\u4e00\u6bb5\u9884\u5b9a\u4e49\u7684\u903b\u8f91\u4ee3\u7801\u3002
\n \u89e6\u53d1\u5668\u7684\u4e3b\u8981\u4f5c\u7528\u662f\u81ea\u52a8\u5316\u5904\u7406\u67d0\u4e9b\u4e1a\u52a1\u89c4\u5219\u6216\u7ef4\u62a4\u6570\u636e\u4e00\u81f4\u6027\u3002<\/p>\nCREATE TRIGGER \u89e6\u53d1\u5668\u540d\u79f0
\n { BEFORE | AFTER } \/\/\u6307\u5b9a\u89e6\u53d1\u5668\u5728\u4e8b\u4ef6\u53d1\u751f\u524d\u8fd8\u662f\u540e\u6267\u884c\u3002
\n { INSERT | UPDATE | DELETE } \/\/\u6307\u5b9a\u89e6\u53d1\u5668\u54cd\u5e94\u7684\u4e8b\u4ef6\u7c7b\u578b\u3002
\n ON \u8868\u540d
\n FOR EACH ROW \/\/\u8868\u793a\u89e6\u53d1\u5668\u5bf9\u6bcf\u4e00\u884c\u6570\u636e\u751f\u6548
\n BEGIN
\n — \u89e6\u53d1\u5668\u903b\u8f91\u4ee3\u7801
\n END;<\/p>\n\/\/\u91cd\u7f6e\u81ea\u589e\u5217\u662f\u6307\u5c06\u6570\u636e\u5e93\u8868\u4e2d\u81ea\u589e\u5217\u7684\u8ba1\u6570\u5668\u503c\u91cd\u65b0\u8bbe\u7f6e\u4e3a\u521d\u59cb\u503c\u6216\u6307\u5b9a\u503c\u3002
\n \/\/\u81ea\u589e\u5217\u662f\u4e00\u79cd\u7279\u6b8a\u7684\u5217，\u5176\u503c\u7531\u6570\u636e\u5e93\u81ea\u52a8\u7ba1\u7406，\u6bcf\u6b21\u63d2\u5165\u65b0\u8bb0\u5f55\u65f6，\u6570\u636e\u5e93
\n\u4f1a\u81ea\u52a8\u4e3a\u5176\u5206\u914d\u4e00\u4e2a\u552f\u4e00\u7684\u3001\u9012\u589e\u7684\u6570\u5b57\u3002
\n \u5e38\u89c1\u7528\u9014：
\n \u4f5c\u4e3a\u4e3b\u952e（Primary Key），\u786e\u4fdd\u6bcf\u884c\u6570\u636e\u7684\u552f\u4e00\u6027\u3002
\n \u81ea\u52a8\u751f\u6210\u5e8f\u53f7\u6216\u5176\u4ed6\u552f\u4e00\u6807\u8bc6\u7b26\u3002
\n \u4f8b\u5b50：id（\u81ea\u589e\u5217，\u4e3b\u952e）
\n \u63d2\u5165\u6570\u636e\u65f6，\u65e0\u9700\u624b\u52a8\u6307\u5b9a id \u7684\u503c：
\n \u6570\u636e\u5e93\u4f1a\u81ea\u52a8\u4e3a id \u5206\u914d\u4e0b\u4e00\u4e2a\u53ef\u7528\u7684\u503c（\u5982 1\u30012\u30013…）\u3002
\n \u5e38\u7528\u65b9\u6cd5：
\n \u4f7f\u7528 TRUNCATE TABLE \u6e05\u7a7a\u8868\u5e76\u81ea\u52a8\u91cd\u7f6e\u3002
\n \u4f7f\u7528 ALTER TABLE \u8868\u540d AUTO_INCREMENT = \u65b0\u503c，，\u624b\u52a8\u8bbe\u7f6e\u81ea\u589e\u503c\u3002 <\/p>\n\n
\u2172. \u4fee\u6539 update<\/h6>\n
— \u4e0d\u5e26\u6761\u4ef6\u7684\u4fee\u6539(\u4f1a\u4fee\u6539\u6240\u6709\u884c)
\nupdate \u8868\u540d set \u5217\u540d = \u503c;<\/p>\n— \u5e26\u6761\u4ef6\u7684\u4fee\u6539
\nupdate \u8868\u540d set \u5217\u540d = \u503c where \u5217\u540d=\u503c;<\/p>\n\/\/SET \u5217\u540d = \u503c：
\n \u6307\u5b9a\u9700\u8981\u4fee\u6539\u7684\u5217\u4ee5\u53ca\u5b83\u7684\u65b0\u503c\u3002
\n \/\/WHERE \u5217\u540d = \u503c：
\n \u6307\u5b9a\u66f4\u65b0\u64cd\u4f5c\u7684\u6761\u4ef6\u3002\u53ea\u6709\u6ee1\u8db3\u6761\u4ef6\u7684\u884c\u624d\u4f1a\u88ab\u66f4\u65b0\u3002 <\/p>\n16. BETWEEN…AND （\u5728\u4ec0\u4e48\u4e4b\u95f4）\u548c IN( \u96c6\u5408)<\/h5>\n
— \u67e5\u8be2\u5e74\u9f84\u5927\u4e8e\u7b49\u4e8e20 \u5c0f\u4e8e\u7b49\u4e8e30
\nSELECT * FROM student WHERE age >= 20 && age <=30;
\nSELECT * FROM student WHERE age >= 20 AND age <=30;
\nSELECT * FROM student WHERE age BETWEEN 20 AND 30;<\/p>\n\u3010\u76f8\u5f53\u4e8e&& \u4e0e AND , BETWEEN AND \u3011<\/p>\n
\/\/from \u8868\u540d where \u5217\u540d<\/p>\n
— \u67e5\u8be2\u5e74\u9f8422\u5c81，18\u5c81，25\u5c81\u7684\u4fe1\u606f
\nSELECT * FROM student WHERE age = 22 OR age = 18 OR age = 25
\nSELECT * FROM student WHERE age IN (22,18,25);<\/p>\n17. is not null(\u4e0d\u4e3anull\u503c) \u4e0e like（\u6a21\u7cca\u67e5\u8be2）\u3001distinct（\u53bb\u9664\u91cd\u590d\u503c）<\/h5>\n
1. is not null
\n— \u67e5\u8be2\u82f1\u8bed\u6210\u7ee9\u4e0d\u4e3anull
\nSELECT * FROM student WHERE english IS NOT NULL;<\/p>\n2.like
\n— \u67e5\u8be2\u59d3\u9a6c\u7684\u6709\u54ea\u4e9b？ like
\nSELECT * FROM student WHERE NAME LIKE '\u9a6c%';
\n— \u67e5\u8be2\u59d3\u540d\u7b2c\u4e8c\u4e2a\u5b57\u662f\u5316\u7684\u4eba
\nSELECT * FROM student WHERE NAME LIKE "_\u5316%";
\n— \u67e5\u8be2\u59d3\u540d\u662f3\u4e2a\u5b57\u7684\u4eba
\nSELECT * FROM student WHERE NAME LIKE '___';
\n[\u6709\u4e09\u4e2a\u6a2a\u7ebf]
\n— \u67e5\u8be2\u59d3\u540d\u4e2d\u5305\u542b\u5fb7\u7684\u4eba
\nSELECT * FROM student WHERE NAME LIKE '%\u5fb7%';<\/p>\n\/\/ _:\u5355\u4e2a\u4efb\u610f\u5b57\u7b26
\n\/\/ %：\u591a\u4e2a\u4efb\u610f\u5b57\u7b26<\/p>\n3.distinct
\nSELECT DISTINCT NAME FROM student ;<\/p>\n— \u5173\u952e\u8bcd DISTINCT \u7528\u4e8e\u8fd4\u56de\u552f\u4e00\u4e0d\u540c\u7684\u503c\u3002\u3010distinct\u3011
\n— \u8bed\u6cd5：SELECT DISTINCT \u5217\u540d\u79f0 FROM \u8868\u540d\u79f0<\/p>\n\/\/\u4ece student \u8868\u4e2d\u67e5\u8be2\u51fa\u6240\u6709\u552f\u4e00\u7684（\u4e0d\u91cd\u590d\u7684）NAME \u503c\u3002
\n \/\/SELECT：\u7528\u4e8e\u4ece\u6570\u636e\u5e93\u8868\u4e2d\u67e5\u8be2\u6570\u636e
\n \/\/DISTINCT：\u7528\u4e8e\u53bb\u9664\u7ed3\u679c\u4e2d\u7684\u91cd\u590d\u503c，\u53ea\u8fd4\u56de\u552f\u4e00\u7684\u3001\u4e0d\u540c\u7684\u503c\u3002
\n \/\/\u7ed3\u679c：\u81ea\u52a8\u8fc7\u6ee4\u6389\u91cd\u590d\u503c\u3002\u53ea\u8fd4\u56de\u552f\u4e00\u7684\u7ed3\u679c\u96c6\u3002 <\/p>\n18. \u805a\u5408\u51fd\u6570：\u5c06\u4e00\u5217\u6570\u636e\u4f5c\u4e3a\u4e00\u4e2a\u6574\u4f53，\u8fdb\u884c\u7eb5\u5411\u7684\u8ba1\u7b97\u3002<\/h5>\n
1.count：\u8ba1\u7b97\u4e2a\u6570<\/p>\n
2.max：\u8ba1\u7b97\u6700\u5927\u503c<\/p>\n
3.min：\u8ba1\u7b97\u6700\u5c0f\u503c<\/p>\n
4.sum：\u8ba1\u7b97\u548c<\/p>\n
5.avg：\u8ba1\u7b97\u5e73\u5747\u6570<\/p>\n
<\/h5>\n
\u6570\u636e\u63a7\u5236\u8bed\u8a00\u3010\u7528\u6237，\u6743\u9650\u3011<\/h5>\n
\u6dfb\u52a0\u7528\u6237<\/h6>\n
CREATE USER '\u7528\u6237\u540d'@'\u4e3b\u673a\u540d' IDENTIFIED BY '\u5bc6\u7801'; <\/p>\n
\u5220\u9664\u7528\u6237<\/h6>\n
DROP USER '\u7528\u6237\u540d'@'\u4e3b\u673a\u540d'; <\/p>\n
\u67e5\u8be2\u6743\u9650<\/h6>\n
— \u67e5\u8be2\u6743\u9650
\nSHOW GRANTS FOR '\u7528\u6237\u540d'@'\u4e3b\u673a\u540d';
\nSHOW GRANTS FOR 'lisi'@'%'; <\/p>\n\u6388\u4e88\u6743\u9650<\/h6>\n
— \u6388\u4e88\u6743\u9650
\ngrant \u6743\u9650\u5217\u8868 on \u6570\u636e\u5e93\u540d.\u8868\u540d to '\u7528\u6237\u540d'@'\u4e3b\u673a\u540d';<\/p>\n— \u7ed9\u5f20\u4e09\u7528\u6237\u6388\u4e88\u6240\u6709\u6743\u9650，\u5728\u4efb\u610f\u6570\u636e\u5e93\u4efb\u610f\u8868\u4e0a
\nGRANT ALL ON *.* TO 'zhangsan'@'localhost'; <\/p>\n\u64a4\u9500\u6743\u9650<\/h6>\n
— \u64a4\u9500\u6743\u9650：
\nrevoke \u6743\u9650\u5217\u8868 on \u6570\u636e\u5e93\u540d.\u8868\u540d from '\u7528\u6237\u540d'@'\u4e3b\u673a\u540d';<\/p>\nREVOKE UPDATE ON db3.`account` FROM 'lisi'@'%';<\/p>\n","protected":false},"excerpt":{"rendered":"
\u524d\u8a00：
\n\u53c2\u8003\u5927\u4f6c\u5185\u5bb9
\n\u3010SQL\u6ce8\u5165\u3011\u5c0f\u767d\u624b\u628a\u624b\u5165\u95e8SQL\u6ce8\u51651-\u6570\u636e\u5e93\u57fa\u7840-CSDN\u535a\u5ba2
\n\u4ecb\u7ecdSQL
\n（1）\u4ec0\u4e48SQL
\nSQL，\u662f\u7528\u4e8e\u7ba1\u7406\u548c\u64cd\u4f5c\u5173\u7cfb\u578b\u6570\u636e\u5e93\u7684\u6807\u51c6\u7f16\u7a0b\u8bed\u8a00，\u6838\u5fc3\u4f5c\u7528\u662f\u5b9e\u73b0\u6570\u636e\u7684\u67e5\u8be2\u3001\u63d2\u5165\u3001\u66f4\u65b0\u3001\u5220\u9664\u7b49\u64cd\u4f5c，\u51e0\u4e4e\u6240\u6709\u5173\u7cfb\u578b\u6570\u636e\u5e93（\u5982MySQL\u3001Oracle\u3001SQL Server）\u90fd\u4f9d\u8d56\u5b83\u5de5\u4f5c\u3002
\n\u7b80\u5355\u6765\u8bf4，\u5b83\u5c31\u50cf\u201c\u6570\u636e\u5e93\u7684\u6307\u4ee4\u9065<\/p>\n","protected":false},"author":2,"featured_media":65084,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[768,100],"topic":[],"class_list":["post-65104","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-server","tag-sql","tag-100"],"yoast_head":"\nSQL\u521d\u8ba4\u8bc6\u4ee5\u53ca\u8bed\u53e5\u5927\u5168 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.wsisp.com\/helps\/65104.html\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"SQL\u521d\u8ba4\u8bc6\u4ee5\u53ca\u8bed\u53e5\u5927\u5168 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"og:description\" content=\"\u524d\u8a00： \u53c2\u8003\u5927\u4f6c\u5185\u5bb9 \u3010SQL\u6ce8\u5165\u3011\u5c0f\u767d\u624b\u628a\u624b\u5165\u95e8SQL\u6ce8\u51651-\u6570\u636e\u5e93\u57fa\u7840-CSDN\u535a\u5ba2 \u4ecb\u7ecdSQL （1）\u4ec0\u4e48SQL SQL，\u662f\u7528\u4e8e\u7ba1\u7406\u548c\u64cd\u4f5c\u5173\u7cfb\u578b\u6570\u636e\u5e93\u7684\u6807\u51c6\u7f16\u7a0b\u8bed\u8a00，\u6838\u5fc3\u4f5c\u7528\u662f\u5b9e\u73b0\u6570\u636e\u7684\u67e5\u8be2\u3001\u63d2\u5165\u3001\u66f4\u65b0\u3001\u5220\u9664\u7b49\u64cd\u4f5c，\u51e0\u4e4e\u6240\u6709\u5173\u7cfb\u578b\u6570\u636e\u5e93（\u5982MySQL\u3001Oracle\u3001SQL Server）\u90fd\u4f9d\u8d56\u5b83\u5de5\u4f5c\u3002 \u7b80\u5355\u6765\u8bf4，\u5b83\u5c31\u50cf\u201c\u6570\u636e\u5e93\u7684\u6307\u4ee4\u9065\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.wsisp.com\/helps\/65104.html\" \/>\n<meta property=\"og:site_name\" content=\"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"article:published_time\" content=\"2026-01-24T06:32:51+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063233-69746781e8257.png\" \/>\n<meta name=\"author\" content=\"admin\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u4f5c\u8005\" \/>\n\t<meta name=\"twitter:data1\" content=\"admin\" \/>\n\t<meta name=\"twitter:label2\" content=\"\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4\" \/>\n\t<meta name=\"twitter:data2\" content=\"12 \u5206\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/65104.html\",\"url\":\"https:\/\/www.wsisp.com\/helps\/65104.html\",\"name\":\"SQL\u521d\u8ba4\u8bc6\u4ee5\u53ca\u8bed\u53e5\u5927\u5168 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\",\"isPartOf\":{\"@id\":\"https:\/\/www.wsisp.com\/helps\/#website\"},\"datePublished\":\"2026-01-24T06:32:51+00:00\",\"dateModified\":\"2026-01-24T06:32:51+00:00\",\"author\":{\"@id\":\"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41\"},\"breadcrumb\":{\"@id\":\"https:\/\/www.wsisp.com\/helps\/65104.html#breadcrumb\"},\"inLanguage\":\"zh-Hans\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.wsisp.com\/helps\/65104.html\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/65104.html#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"\u9996\u9875\",\"item\":\"https:\/\/www.wsisp.com\/helps\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"SQL\u521d\u8ba4\u8bc6\u4ee5\u53ca\u8bed\u53e5\u5927\u5168\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/#website\",\"url\":\"https:\/\/www.wsisp.com\/helps\/\",\"name\":\"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\",\"description\":\"\u9999\u6e2f\u670d\u52a1\u5668_\u9999\u6e2f\u4e91\u670d\u52a1\u5668\u8d44\u8baf_\u670d\u52a1\u5668\u5e2e\u52a9\u6587\u6863_\u670d\u52a1\u5668\u6559\u7a0b\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.wsisp.com\/helps\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"zh-Hans\"},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41\",\"name\":\"admin\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"zh-Hans\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery\",\"contentUrl\":\"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery\",\"caption\":\"admin\"},\"sameAs\":[\"http:\/\/wp.wsisp.com\"],\"url\":\"https:\/\/www.wsisp.com\/helps\/author\/admin\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"SQL\u521d\u8ba4\u8bc6\u4ee5\u53ca\u8bed\u53e5\u5927\u5168 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.wsisp.com\/helps\/65104.html","og_locale":"zh_CN","og_type":"article","og_title":"SQL\u521d\u8ba4\u8bc6\u4ee5\u53ca\u8bed\u53e5\u5927\u5168 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","og_description":"\u524d\u8a00： \u53c2\u8003\u5927\u4f6c\u5185\u5bb9 \u3010SQL\u6ce8\u5165\u3011\u5c0f\u767d\u624b\u628a\u624b\u5165\u95e8SQL\u6ce8\u51651-\u6570\u636e\u5e93\u57fa\u7840-CSDN\u535a\u5ba2 \u4ecb\u7ecdSQL （1）\u4ec0\u4e48SQL SQL，\u662f\u7528\u4e8e\u7ba1\u7406\u548c\u64cd\u4f5c\u5173\u7cfb\u578b\u6570\u636e\u5e93\u7684\u6807\u51c6\u7f16\u7a0b\u8bed\u8a00，\u6838\u5fc3\u4f5c\u7528\u662f\u5b9e\u73b0\u6570\u636e\u7684\u67e5\u8be2\u3001\u63d2\u5165\u3001\u66f4\u65b0\u3001\u5220\u9664\u7b49\u64cd\u4f5c，\u51e0\u4e4e\u6240\u6709\u5173\u7cfb\u578b\u6570\u636e\u5e93（\u5982MySQL\u3001Oracle\u3001SQL Server）\u90fd\u4f9d\u8d56\u5b83\u5de5\u4f5c\u3002 \u7b80\u5355\u6765\u8bf4，\u5b83\u5c31\u50cf\u201c\u6570\u636e\u5e93\u7684\u6307\u4ee4\u9065","og_url":"https:\/\/www.wsisp.com\/helps\/65104.html","og_site_name":"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","article_published_time":"2026-01-24T06:32:51+00:00","og_image":[{"url":"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/01\/20260124063233-69746781e8257.png"}],"author":"admin","twitter_card":"summary_large_image","twitter_misc":{"\u4f5c\u8005":"admin","\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4":"12 \u5206"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/www.wsisp.com\/helps\/65104.html","url":"https:\/\/www.wsisp.com\/helps\/65104.html","name":"SQL\u521d\u8ba4\u8bc6\u4ee5\u53ca\u8bed\u53e5\u5927\u5168 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","isPartOf":{"@id":"https:\/\/www.wsisp.com\/helps\/#website"},"datePublished":"2026-01-24T06:32:51+00:00","dateModified":"2026-01-24T06:32:51+00:00","author":{"@id":"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41"},"breadcrumb":{"@id":"https:\/\/www.wsisp.com\/helps\/65104.html#breadcrumb"},"inLanguage":"zh-Hans","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.wsisp.com\/helps\/65104.html"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.wsisp.com\/helps\/65104.html#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"\u9996\u9875","item":"https:\/\/www.wsisp.com\/helps"},{"@type":"ListItem","position":2,"name":"SQL\u521d\u8ba4\u8bc6\u4ee5\u53ca\u8bed\u53e5\u5927\u5168"}]},{"@type":"WebSite","@id":"https:\/\/www.wsisp.com\/helps\/#website","url":"https:\/\/www.wsisp.com\/helps\/","name":"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","description":"\u9999\u6e2f\u670d\u52a1\u5668_\u9999\u6e2f\u4e91\u670d\u52a1\u5668\u8d44\u8baf_\u670d\u52a1\u5668\u5e2e\u52a9\u6587\u6863_\u670d\u52a1\u5668\u6559\u7a0b","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.wsisp.com\/helps\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"zh-Hans"},{"@type":"Person","@id":"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41","name":"admin","image":{"@type":"ImageObject","inLanguage":"zh-Hans","@id":"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/image\/","url":"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery","contentUrl":"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery","caption":"admin"},"sameAs":["http:\/\/wp.wsisp.com"],"url":"https:\/\/www.wsisp.com\/helps\/author\/admin"}]}},"_links":{"self":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/posts\/65104","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/comments?post=65104"}],"version-history":[{"count":0,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/posts\/65104\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/media\/65084"}],"wp:attachment":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/media?parent=65104"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/categories?post=65104"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/tags?post=65104"},{"taxonomy":"topic","embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/topic?post=65104"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- \u00a0\/* *\/\u00a0：\u591a\u884c\u6ce8\u91ca，\u00a0\/*\u00a0\u548c\u00a0*\/\u00a0\u4e4b\u95f4\u7684\u6240\u6709\u5185\u5bb9\u90fd\u4f1a\u88ab\u6ce8\u91ca（\u53ef\u4ee5\u8de8\u591a\u884c）\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- — \u7a7a\u683c\u00a0（\u6ce8\u610f\u00a0—\u00a0\u540e\u5fc5\u987b\u8ddf\u7a7a\u683c）：\u4e5f\u662f\u5355\u884c\u6ce8\u91ca，\u4ece\u00a0— \u7a7a\u683c\u00a0\u5f00\u59cb\u5230\u884c\u5c3e\u751f\u6548\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- #\u00a0：\u5355\u884c\u6ce8\u91ca，\u4ece\u00a0#\u00a0\u5f00\u59cb\u5230\u884c\u5c3e\u7684\u5185\u5bb9\u90fd\u4f1a\u88ab\u89c6\u4e3a\u6ce8\u91ca\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \u5173\u952e\u89c4\u5219<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \n
- \n
- \n
- \u7edf\u4e00\u5b57\u7b26\u96c6<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \n
- \u89e3\u51b3\u5b57\u7b26\u7f16\u7801\u95ee\u9898<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \n
- \u5982\u679c\u67d0\u6761\u8bb0\u5f55\u5728\u5de6\u4fa7\u8868\u4e2d\u6ca1\u6709\u5339\u914d\u9879，\u5219\u5de6\u4fa7\u8868\u7684\u5b57\u6bb5\u503c\u4f1a\u663e\u793a\u4e3a NULL\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \u672a\u5339\u914d\u7684\u5de6\u4fa7\u8868\u5b57\u6bb5\u663e\u793a\u4e3a NULL：<\/li>\n<\/ul>\n
- \u5373\u4f7f\u67d0\u4e9b\u8bb0\u5f55\u5728\u5de6\u4fa7\u8868\u4e2d\u6ca1\u6709\u5339\u914d\u9879，\u53f3\u4fa7\u8868\u7684\u8bb0\u5f55\u4ecd\u7136\u4f1a\u88ab\u4fdd\u7559\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \u4fdd\u7559\u53f3\u4fa7\u8868\u7684\u6240\u6709\u8bb0\u5f55：<\/li>\n<\/ul>\n
- \u5982\u679c\u67d0\u6761\u8bb0\u5f55\u5728\u4ece\u8868\u4e2d\u6ca1\u6709\u5339\u914d\u9879，\u5219\u4ece\u8868\u7684\u5b57\u6bb5\u503c\u4f1a\u663e\u793a\u4e3a NULL\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \u672a\u5339\u914d\u7684\u4ece\u8868\u5b57\u6bb5\u663e\u793a\u4e3a NULL：<\/li>\n<\/ul>\n
- \u5373\u4f7f\u67d0\u4e9b\u8bb0\u5f55\u5728\u4ece\u8868\u4e2d\u6ca1\u6709\u5339\u914d\u9879，\u4e3b\u8868\u7684\u8bb0\u5f55\u4ecd\u7136\u4f1a\u88ab\u4fdd\u7559\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \u4fdd\u7559\u4e3b\u8868\u7684\u6240\u6709\u8bb0\u5f55：<\/li>\n<\/ul>\n
- \n
- \n
- \u4f5c\u7528：<\/li>\n<\/ul>\n
- \u5916\u952e\u662f\u4e00\u4e2a\u8868\u4e2d\u7684\u5b57\u6bb5（\u6216\u5b57\u6bb5\u7ec4\u5408），\u5b83\u7684\u503c\u5fc5\u987b\u51fa\u73b0\u5728\u53e6\u4e00\u4e2a\u8868\u7684\u4e3b\u952e\u6216\u552f\u4e00\u952e\u4e2d\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
- \n
- \u5b9a\u4e49：<\/li>\n<\/ul>\n
- \n
- \n
- \n
- \n
- \n
- \n