{"id":11461,"date":"2025-06-12T11:09:45","date_gmt":"2025-06-12T03:09:45","guid":{"rendered":"https:\/\/egonlin.com\/?p=11461"},"modified":"2025-06-12T16:24:39","modified_gmt":"2025-06-12T08:24:39","slug":"%e6%ad%a3%e7%a1%ae%e4%bd%bf%e7%94%a8%e7%b4%a2%e5%bc%95","status":"publish","type":"post","link":"https:\/\/egonlin.com\/?p=11461","title":{"rendered":"\u6b63\u786e\u4f7f\u7528\u7d22\u5f15"},"content":{"rendered":"

\u4e00 \u7d22\u5f15\u547d\u4e2d\u4e5f\u672a\u5fc5\u4f1a\u52a0\u901f<\/strong><\/p>\n

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\n<\/strong><\/p>\n

1 \u8303\u56f4\u95ee\u9898\uff0c\u6216\u8005\u8bf4\u6761\u4ef6\u4e0d\u660e\u786e\uff0c\u6761\u4ef6\u4e2d\u51fa\u73b0\u8fd9\u4e9b\u7b26\u53f7\u6216\u5173\u952e\u5b57\uff1a<\/strong>>\u3001>=\u3001<\u3001<=\u3001!= \u3001between…and…\u3001like\u3001<\/strong><\/p>\n

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\"\"<\/div><\/strong><\/p>\n

\u4e0d\u7b49\u4e8e\uff01=<\/p>\n

\"\"<\/div><\/p>\n

between …and…<\/p>\n

\"\"<\/div><\/p>\n

like\uff1a%\u6216\u8005_\u5e94\u8be5\u653e\u5728\u53f3\u8fb9\uff0c\u5e76\u4e14\u5de6\u8fb9\u7684\u5b57\u7b26\u5e94\u8be5\u5c3d\u53ef\u80fd\u5730\u7cbe\u786e\u4e00\u4e9b\uff0c\u8fd9\u6837\u9501\u5b9a\u7684\u8303\u56f4\u624d\u4f1a\u5c0f\u4e00\u4e9b\uff0c\u4f8b\u5982like “egon3%”\u800c\u4e0d\u662flike “%egon3″\u3001like “eg%”<\/p>\n

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2\u00a0\u5c3d\u91cf\u9009\u62e9\u533a\u5206\u5ea6\u9ad8\u7684\u5217\u4f5c\u4e3a\u7d22\u5f15,\u533a\u5206\u5ea6\u7684\u516c\u5f0f\u662fcount(distinct col)\/count(*)\uff0c\u8868\u793a\u5b57\u6bb5\u4e0d\u91cd\u590d\u7684\u6bd4\u4f8b\uff0c\u6bd4\u4f8b\u8d8a\u5927\u6211\u4eec\u626b\u63cf\u7684\u8bb0\u5f55\u6570\u8d8a\u5c11\uff0c\u552f\u4e00\u952e\u7684\u533a\u5206\u5ea6\u662f1\uff0c\u800c\u4e00\u4e9b\u72b6\u6001\u3001\u6027\u522b\u5b57\u6bb5\u53ef\u80fd\u5728\u5927\u6570\u636e\u9762\u524d\u533a\u5206\u5ea6\u5c31\u662f0\uff0c\u90a3\u53ef\u80fd\u6709\u4eba\u4f1a\u95ee\uff0c\u8fd9\u4e2a\u6bd4\u4f8b\u6709\u4ec0\u4e48\u7ecf\u9a8c\u503c\u5417\uff1f\u4f7f\u7528\u573a\u666f\u4e0d\u540c\uff0c\u8fd9\u4e2a\u503c\u4e5f\u5f88\u96be\u786e\u5b9a\uff0c\u4e00\u822c\u9700\u8981join\u7684\u5b57\u6bb5\u6211\u4eec\u90fd\u8981\u6c42\u662f0.1\u4ee5\u4e0a\uff0c\u5373\u5e73\u57471\u6761\u626b\u63cf10\u6761\u8bb0\u5f55<\/strong><\/p>\n

#\u5148\u628a\u8868\u4e2d\u7684\u7d22\u5f15\u90fd\u5220\u9664\uff0c\u8ba9\u6211\u4eec\u4e13\u5fc3\u7814\u7a76\u533a\u5206\u5ea6\u7684\u95ee\u9898<\/span><\/p>\n

#\u5148\u628a\u8868\u4e2d\u7684\u7d22\u5f15\u90fd\u5220\u9664\uff0c\u8ba9\u6211\u4eec\u4e13\u5fc3\u7814\u7a76\u533a\u5206\u5ea6\u7684\u95ee\u9898 mysql> desc s1; +——–+————-+——+—–+———+——-+ | Field | Type | Null | Key | Default | Extra | +——–+————-+——+—–+———+——-+ | id | int(11) | YES | MUL | NULL | | | name | varchar(20) | YES | | NULL | | | gender | char(5) | YES | | NULL | | | email | varchar(50) | YES | MUL | NULL | | +——–+————-+——+—–+———+——-+ 4 rows in set (0.00 sec) mysql> drop index a on s1; Query OK, 0 rows affected (0.20 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> drop index d on s1; Query OK, 0 rows affected (0.18 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc s1; +——–+————-+——+—–+———+——-+ | Field | Type | Null | Key | Default | Extra | +——–+————-+——+—–+———+——-+ | id | int(11) | YES | | NULL | | | name | varchar(20) | YES | | NULL | | | gender | char(5) | YES | | NULL | | | email | varchar(50) | YES | | NULL | | +——–+————-+——+—–+———+——-+ 4 rows in set (0.00 sec)

\"\"<\/div>
\n\u5206\u6790\u539f\u56e0<\/span><\/p>\n
\n
\u6211\u4eec\u7f16\u5199\u5b58\u50a8\u8fc7\u7a0b\u4e3a\u8868s1\u6279\u91cf\u6dfb\u52a0\u8bb0\u5f55\uff0cname\u5b57\u6bb5\u7684\u503c\u5747\u4e3aegon\uff0c\u4e5f\u5c31\u662f\u8bf4name\u8fd9\u4e2a\u5b57\u6bb5\u7684\u533a\u5206\u5ea6\u5f88\u4f4e\uff08gender\u5b57\u6bb5\u4e5f\u662f\u4e00\u6837\u7684\uff0c\u6211\u4eec\u7a0d\u540e\u518d\u642d\u7406\u5b83\uff09\r\n\r\n\u56de\u5fc6b+\u6811\u7684\u7ed3\u6784\uff0c\u67e5\u8be2\u7684\u901f\u5ea6\u4e0e\u6811\u7684\u9ad8\u5ea6\u6210\u53cd\u6bd4\uff0c\u8981\u60f3\u5c06\u6811\u7684\u9ad8\u4f4e\u63a7\u5236\u7684\u5f88\u4f4e\uff0c\u9700\u8981\u4fdd\u8bc1\uff1a\u5728\u67d0\u4e00\u5c42\u5185\u6570\u636e\u9879\u5747\u662f\u6309\u7167\u4ece\u5de6\u5230\u53f3\uff0c\u4ece\u5c0f\u5230\u5927\u7684\u987a\u5e8f\u4f9d\u6b21\u6392\u5f00\uff0c\u5373\u5de61<\u5de62<\u5de63<...\r\n\r\n\u800c\u5bf9\u4e8e\u533a\u5206\u5ea6\u4f4e\u7684\u5b57\u6bb5\uff0c\u65e0\u6cd5\u627e\u5230\u5927\u5c0f\u5173\u7cfb\uff0c\u56e0\u4e3a\u503c\u90fd\u662f\u76f8\u7b49\u7684\uff0c\u6beb\u65e0\u7591\u95ee\uff0c\u8fd8\u60f3\u8981\u7528b+\u6811\u5b58\u653e\u8fd9\u4e9b\u7b49\u503c\u7684\u6570\u636e\uff0c\u53ea\u80fd\u589e\u52a0\u6811\u7684\u9ad8\u5ea6\uff0c\u5b57\u6bb5\u7684\u533a\u5206\u5ea6\u8d8a\u4f4e\uff0c\u5219\u6811\u7684\u9ad8\u5ea6\u8d8a\u9ad8\u3002\u6781\u7aef\u7684\u60c5\u51b5\uff0c\u7d22\u5f15\u5b57\u6bb5\u7684\u503c\u90fd\u4e00\u6837\uff0c\u90a3\u4e48b+\u6811\u51e0\u4e4e\u6210\u4e86\u4e00\u6839\u68cd\u3002\u672c\u4f8b\u4e2d\u5c31\u662f\u8fd9\u79cd\u6781\u7aef\u7684\u60c5\u51b5\uff0cname\u5b57\u6bb5\u6240\u6709\u7684\u503c\u5747\u4e3a'egon'\r\n\r\n#\u73b0\u5728\u6211\u4eec\u5f97\u51fa\u4e00\u4e2a\u7ed3\u8bba\uff1a\u4e3a\u533a\u5206\u5ea6\u4f4e\u7684\u5b57\u6bb5\u5efa\u7acb\u7d22\u5f15\uff0c\u7d22\u5f15\u6811\u7684\u9ad8\u5ea6\u4f1a\u5f88\u9ad8\uff0c\u7136\u800c\u8fd9\u5177\u4f53\u4f1a\u5e26\u6765\u4ec0\u4e48\u5f71\u54cd\u5462\uff1f\uff1f\uff1f\r\n\r\n#1\uff1a\u5982\u679c\u6761\u4ef6\u662fname='xxxx',\u90a3\u4e48\u80af\u5b9a\u662f\u53ef\u4ee5\u7b2c\u4e00\u65f6\u95f4\u5224\u65ad\u51fa'xxxx'\u662f\u4e0d\u5728\u7d22\u5f15\u6811\u4e2d\u7684\uff08\u56e0\u4e3a\u6811\u4e2d\u6240\u6709\u7684\u503c\u5747\u4e3a'egon\u2019\uff09\uff0c\u6240\u4ee5\u67e5\u8be2\u901f\u5ea6\u5f88\u5feb\r\n\r\n#2\uff1a\u5982\u679c\u6761\u4ef6\u6b63\u597d\u662fname='egon',\u67e5\u8be2\u65f6\uff0c\u6211\u4eec\u6c38\u8fdc\u65e0\u6cd5\u4ece\u6811\u7684\u67d0\u4e2a\u4f4d\u7f6e\u5f97\u5230\u4e00\u4e2a\u660e\u786e\u7684\u8303\u56f4\uff0c\u53ea\u80fd\u5f80\u4e0b\u627e\uff0c\u5f80\u4e0b\u627e\uff0c\u5f80\u4e0b\u627e\u3002\u3002\u3002\u8fd9\u4e0e\u5168\u8868\u626b\u63cf\u7684IO\u6b21\u6570\u6ca1\u6709\u591a\u5927\u533a\u522b\uff0c\u6240\u4ee5\u901f\u5ea6\u5f88\u6162<\/pre>\n<\/div>\n
3 \u7d22\u5f15\u5217\u4e0d\u80fd\u53c2\u4e0e\u8ba1\u7b97\uff0c\u4fdd\u6301\u5217\u201c\u5e72\u51c0\u201d\uff0c\u6bd4\u5982from_unixtime(create_time) = \u20192014-05-29\u2019\u5c31\u4e0d\u80fd\u4f7f\u7528\u5230\u7d22\u5f15\uff0c\u539f\u56e0\u5f88\u7b80\u5355\uff0cb+\u6811\u4e2d\u5b58\u7684\u90fd\u662f\u6570\u636e\u8868\u4e2d\u7684\u5b57\u6bb5\u503c\uff0c\u4f46\u8fdb\u884c\u68c0\u7d22\u65f6\uff0c\u9700\u8981\u628a\u6240\u6709\u5143\u7d20\u90fd\u5e94\u7528\u51fd\u6570\u624d\u80fd\u6bd4\u8f83\uff0c\u663e\u7136\u6210\u672c\u592a\u5927\u3002\u6240\u4ee5\u8bed\u53e5\u5e94\u8be5\u5199\u6210create_time = unix_timestamp(\u20192014-05-29\u2019)<\/strong><\/p>\n
\"\"<\/div><\/p>\n
4 \u7d22\u5f15\u4e0b\u63a8\u6280\u672f\u7684\u5e94\u7528<\/strong><\/p>\n
 <\/p>\n
\u7d22\u5f15\u4e0b\u63a8\u6280\u672f\uff1a\u6307\u7684\u662f\u5728\u8054\u5408\u7d22\u5f15\u7684\u57fa\u7840\u4e0a\u53ef\u4ee5\u7ee7\u7eed\u5f80\u540e\u6bd4\u8f83\u540e\u7eed\u7684\u5b57\u6bb5\u6765\u8fdb\u4e00\u6b65\u7b5b\u9009\uff0c\u4ee5\u6b64\u51cf\u5c11\u56de\u8868\u64cd\u4f5c\uff0c5.6\u624d\u6709\u9ed8\u8ba4\u5c31\u5f00\u542fhttps:\/\/zhuanlan.zhihu.com\/p\/408570713
\n\u8054\u5408\u7d22\u5f15\u5c31\u662f\u628an\u4e2a\u5b57\u6bb5\u7ec4\u5408\u5230\u4e00\u8d77\u5f53\u6210key\u503c\uff0c\u8054\u5408\u7d22\u5f15\u80af\u5b9a\u5c5e\u4e8e\u8f85\u52a9\u7d22\u5f15\uff0c\u4e0e\u5355\u4e2a\u5b57\u6bb5\u5236\u4f5c\u7684\u8f85\u52a9\u7d22\u5f15\u76f8\u540c\u7684\u662f\uff0c\u4ed6\u4eec\u7684\u53f6\u5b50\u8282\u70b9\u653e\u7684\u90fd\u662f\u7d22\u5f15\u503c\u53ca\u5176\u5bf9\u5e94\u7684\u4e3b\u5efa\uff0c\u4e0d\u540c\u7684\u7684\u662f\u8054\u5408\u7d22\u5f15\u7684\u53f6\u5b50\u8282\u70b9\u653e\u7684\u7d22\u5f15\u503c\u662f\u7531\u591a\u4e2a\u5b57\u6bb5\u62fc\u5230\u4e00\u8d77\u7684\uff0c\u7d22\u5f15\u4e0b\u63a8\u5c31\u5229\u7528\u8fd9\u62fc\u8d77\u6765\u7684\u591a\u4e2a\u5b57\u6bb5\uff0c\u6328\u4e2a\u6bd4\u8f83\uff0c\u76f4\u5230\u7b5b\u9009\u51fa\u4e00\u4e2a\u6700\u7ec8\u7684\u7ed3\u679c\uff0c\u6700\u540e\u90a3\u90a3\u4e9b\u8fd9\u4e9b\u7ed3\u679c\u5bf9\u5e94\u7684\u4e3b\u5efaid\u53bb\u805a\u96c6\u7d22\u5f15\u91cc\u8fdb\u884c\u56de\u8868\u67e5\u8be2<\/p>\n
 <\/p>\n
and\/or<\/strong><\/p>\n
\n
\n
#1\u3001\u8fde\u7eed\u7684\u591a\u4e2aand\u6761\u4ef6\r\n\u6761\u4ef61 and \u6761\u4ef62 and \u6761\u4ef63\uff0c\u6240\u6709\u6761\u4ef6\u90fd\u6210\u7acb\u624d\u7b97\u6210\u7acb\uff0c\u9501\u5b9a\u7684\u8303\u56f4\u5c0f\r\n\u6240\u4ee5\u5bf9\u4e8e\u8fde\u7eed\u591a\u4e2aand\u6761\u4ef6\uff0c\u5148\u5224\u65ad\u54ea\u4e00\u4e2a\u5e76\u6ca1\u6709\u5dee\u522b\uff0c\u53cd\u6b63\u6700\u540e\u90fd\u9700\u8981\u6210\u7acb\u624d\u884c\uff0c\r\n\u56e0\u6b64mysql\u7684\u4f18\u5316\u5668\u5bf9\u4e8e\u8fde\u7eed\u591a\u4e2aand\u6761\u4ef6\uff0c\u4f1a\u5236\u5b9a\u51fa\u6240\u6709\u53ef\u80fd\u7684\u67e5\u8be2\u8ba1\u5212\uff1a\r\n\u8ba1\u52121\uff1a\u4ee5\u6761\u4ef61\u7684\u5b57\u6bb5\u4e3a\u57fa\u7840\u7b5b\u9009\u51fa\u4e00\u6279\u8bb0\u5f55\uff0c\u7136\u540e\u5728\u9a8c\u8bc1\u8fd9\u6279\u8bb0\u5f55\u662f\u5426\u7b26\u5408\u6761\u4ef62\u4e0e\u6761\u4ef63\r\n\u8ba1\u52122\uff1a\u4ee5\u6761\u4ef62\u7684\u5b57\u6bb5\u4e3a\u57fa\u7840\u7b5b\u9009\u51fa\u4e00\u6279\u8bb0\u5f55\uff0c\u7136\u540e\u5728\u9a8c\u8bc1\u8fd9\u6279\u8bb0\u5f55\u662f\u5426\u7b26\u5408\u6761\u4ef61\u4e0e\u6761\u4ef63\r\n\u8ba1\u52123\uff1a\u4ee5\u6761\u4ef63\u7684\u5b57\u6bb5\u4e3a\u57fa\u7840\u7b5b\u9009\u51fa\u4e00\u6279\u8bb0\u5f55\uff0c\u7136\u540e\u5728\u9a8c\u8bc1\u8fd9\u6279\u8bb0\u5f55\u662f\u5426\u7b26\u5408\u6761\u4ef61\u4e0e\u6761\u4ef62\r\n\r\n\u6700\u7ec8mysql\u4f18\u5316\u5668\u4f1a\u9009\u51fa\u4e00\u4e2a\u6700\u4f73\u7684\u8ba1\u5212\uff0c\u5373\u4ee5\u67d0\u4e2a\u6761\u4ef6\u7684\u5b57\u6bb5\u503c\u4e3a\u57fa\u7840\u7b5b\u9009\u51fa\u7684\u8bb0\u5f55\u6700\u5c0f\uff0c\u8fd9\u5c31\u662f\u7d22\u5f15\u4e0b\u63a8\u6280\u672f\uff0cegon\u8001\u5e08\u7ed9\u4e3e\u4e2a\u4f8b\u5b50\u4f60\u4e00\u4e0b\u5b50\u5c31\u660e\u767d\u4e86\r\n\u4f8b\u5982\uff1a\u76f8\u4eb2\uff0c\u4f60\u9700\u8981\u4ece\u4e00\u5343\u4eba\u4e2d\u9009\u51fa\u7b26\u5408\u81ea\u5df1\u6761\u4ef6\u7684\u76f8\u4eb2\u5bf9\u8c61\uff0c\u8fd9\u4e00\u5343\u4eba\u5c31\u597d\u6bd4\u4e00\u5f20\u8868\u4e2d\u7684\u4e00\u5343\u6761\u6570\u636e\uff0c\u4e00\u7cfb\u5217and\u6761\u4ef6\u5c31\u662f\u4f60\u7684\u62e9\u5076\u6807\u51c6\uff08\u62e9\u5076\u6807\u51c6\u80af\u5b9a\u4e0d\u80fd\u662f\u4e00\u7cfb\u5217or\u6761\u4ef6\uff0c\u4f60\u8bf4egon\u8bf4\u7684\u5bf9\u4e0d\u5bf9\uff09\r\n    \u4f60\u7684\u62e9\u5076\u6761\u4ef6\u662f\uff1a\u6027\u522b=\u5973 and \u5e74\u9f84 = 18 and \u957f\u76f8 = \u597d\u770b\r\n    \u95ee\uff0c\u5982\u4f55\u7b5b\u9009\u4f1a\u4ee5\u6700\u5feb\u7684\u901f\u5ea6\u627e\u51fa\u9002\u914d\u5bf9\u8c61\uff0c\u5f88\u660e\u663e\uff0c\u4e0d\u5e94\u8be5\u6309\u7167\u4ece\u5de6\u5230\u53f3\u7684\u987a\u5e8f\u68c0\u7d22\uff0c\u56e0\u4e3a\u201c\u6027\u522b=\u5973\u201d\u7684\u4e00\u5927\u5806\u554a\uff0c\r\n    \u65e2\u7136\u591a\u4e2aand\u6761\u4ef6\u4e00\u5b9a\u662f\u9700\u8981\u540c\u65f6\u6210\u7acb\u7684\u624d\u53ef\u4ee5\uff0c\u90a3\u4e48\u65e0\u8bba\u5148\u6bd4\u54ea\u4e2a\u90fd\u53ef\u4ee5\u554a\uff0c\u53cd\u6b63\u6700\u7ec8\u90fd\u5f97\u6ee1\u8db3\u6761\u4ef6\u624d\u53ef\u4ee5\uff0c\u6240\u4ee5\u6211\u4eec\r\n    \u5b8c\u6574\u53ef\u4ee5\u5148\u4ee5\u4e00\u4e2a\u6bd4\u8f83\u82db\u523b\uff08\u5373\u9501\u5b9a\u8303\u56f4\u8f83\u5c0f\u7684\u6761\u4ef6\uff09\u6761\u4ef6\u9501\u5b9a\u4e00\u5c0f\u90e8\u5206\u4eba\uff0c\u7136\u540e\u518d\u4ece\u8fd9\u4e00\u4e9b\u90e8\u5206\u4eba\u7fa4\u4e2d\u5224\u65ad\u662f\u5426\u7b26\u5408\u5176\u4ed6\u6761\u4ef6\r\n    \u6bd4\u5982\u5148\u62ff\u7740\"\u957f\u76f8=\u597d\u770b\"\u8fd9\u4e2a\u6761\u4ef6\u6765\u7b5b\u9009\uff0c\u90a3\u4e48\u4e00\u5343\u4eba\u53ef\u80fd\u53ea\u5269\u4e0b\u4e8610\u4e2a\u4eba\u4e86\uff0c\u7136\u540e\u5728\u5224\u65ad\u8fd9\u5341\u4e2a\u4eba\u662f\u5426\u6ee1\u8db3\u201c\u6027\u522b=\u5973 and \u5e74\u9f84=18\u201c\u8fd9\u6837\u6548\u7387\u5c31\u9ad8\u4e86\r\n    \u8fd9\u5c31\u662f\u7d22\u5f15\u4e0b\u63a8\u6280\u672f\u7684\u539f\u7406\uff0c\u5373\u8fde\u7eed\u7684\u591a\u4e2aand\u6761\u4ef6\u5e76\u975e\u662f\u6309\u7167\u4ece\u5de6\u5230\u53f3\u7684\u987a\u5e8f\u8ba1\u7b97\u7684\uff0c\u4f46\u8fd9\u79cd\u6280\u672f\u4e5f\u4ec5\u9002\u7528\u4e8e\u8fde\u7eed\u7684\u591a\u4e2aand\u6761\u4ef6\r\n    \r\n#2\u3001\u8fde\u7eed\u7684\u591a\u4e2aor\u6761\u4ef6\r\n\u6761\u4ef61 or \u6761\u4ef62 or \u6761\u4ef63\uff0c\u53ea\u8981\u6709\u4e00\u4e2a\u6761\u4ef6\u6210\u7acb\u5219\u6700\u7ec8\u7ed3\u679c\u5c31\u6210\u7acb\uff0c\u9501\u5b9a\u7684\u8303\u56f4\u5927\r\n\r\n\u5bf9\u4e8e\u8fde\u7eed\u7684\u591a\u4e2aor\u6761\u4ef6\uff0cmysql\u53ea\u80fd\u6309\u7167\u6761\u4ef6\u7684\u987a\u5e8f\uff0c\u4ece\u5de6\u5230\u53f3\u4f9d\u6b21\u5224\u65ad\u4e86\uff0cegon\u8001\u5e08\u8fd8\u662f\u7ed9\u4f60\u4e3e\u4e2a\u65b9\u4fbf\u7406\u89e3\u7684\u4f8b\u5b50\r\n\u4f8b\u5982\uff1a\u9009\u51fa\u6c7d\u8f66\u7684\u6b8b\u6b21\u54c1\uff0c\u4e00\u5b9a\u662f\u4e00\u7cfb\u5217or\u6761\u4ef6\uff0c\u56e0\u4e3a\u4f46\u51e1\u4e00\u4e2a\u96f6\u4ef6\u574f\u4e86\u5c31\u7b97\u662f\u6b8b\u6b21\u54c1\r\n    \u4f60\u7684\u7b5b\u9009\u6761\u4ef6\u662f\uff1a\u65b9\u5411\u76d8\u574f\u4e86 or \u8f6e\u6bc2\u574f\u4e86 or \u5239\u8f66\u574f\u4e86\r\n    \u8fd9\u4e2a\u65f6\u5019\u4f60\u53ea\u80fd\u6309\u7167\u4ece\u5de6\u5230\u53f3\u7684\u987a\u5e8f\u4f9d\u6b21\u5224\u65ad\u6761\u4ef6\u6765\u8fdb\u884c\u7b5b\u9009\u4e86\uff0c\u6839\u672c\u4e0d\u80fd\u50cf\u8fde\u7eed\u591a\u4e2aand\u90a3\u6837\u5148\u7528\u67d0\u4e2a\u6761\u4ef6\u9501\u5b9a\u4e00\u4e2a\u5c0f\u8303\u56f4\uff0c\u4f8b\u5982\u4f60\u4ee5\u8f6e\u6bc2\u574f\u4e86\u4e3a\u6761\u4ef6\r\n    \u7b5b\u51fa\u4e00\u4e9b\u6b8b\u6b21\u54c1\uff0c\u5e76\u4e0d\u80fd\u5728\u6b64\u57fa\u7840\u4e0a\u5224\u65ad\u5176\u4ed6\u63d0\u4ea4\uff0c\u56e0\u4e3a\u4f46\u51e1\u662f\u4e00\u4e2a\u6761\u4ef6\u6ee1\u8db3\uff0c\u90fd\u7b97\u662f\u6b8b\u6b21\u54c1<\/pre>\n
\"\"<\/div><\/span><\/p>\n<\/div>\n
\u5728\u5de6\u8fb9\u6761\u4ef6\u6210\u7acb\u4f46\u662f\u7d22\u5f15\u5b57\u6bb5\u7684\u533a\u5206\u5ea6\u4f4e\u7684\u60c5\u51b5\u4e0b\uff08name\u4e0egender\u5747\u5c5e\u4e8e\u8fd9\u79cd\u60c5\u51b5\uff09\uff0c\u4f1a\u4f9d\u6b21\u5f80\u53f3\u627e\u5230\u4e00\u4e2a\u533a\u5206\u5ea6\u9ad8\u7684\u7d22\u5f15\u5b57\u6bb5\uff0c\u52a0\u901f\u67e5\u8be2<\/div>\n
\"\"<\/div><\/div>\n
\"\"<\/div><\/div>\n
\n
\u7ecf\u8fc7\u5206\u6790\uff0c\u5728\u6761\u4ef6\u4e3aname=’egon’ and gender=’male’ and id>333 and email=’xxx’\u7684\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u5b8c\u5168\u6ca1\u5fc5\u8981\u4e3a\u524d\u4e09\u4e2a\u6761\u4ef6\u7684\u5b57\u6bb5\u52a0\u7d22\u5f15\uff0c\u56e0\u4e3a\u53ea\u80fd\u7528\u4e0aemail\u5b57\u6bb5\u7684\u7d22\u5f15\uff0c\u524d\u4e09\u4e2a\u5b57\u6bb5\u7684\u7d22\u5f15\u53cd\u800c\u4f1a\u964d\u4f4e\u6211\u4eec\u7684\u67e5\u8be2\u6548\u7387<\/p>\n
\"\"<\/div><\/p>\n<\/div>\n<\/div>\n
5 \u6700\u5de6\u524d\u7f00\u5339\u914d\u539f\u5219\uff08\u8be6\u89c1\u7b2c\u516b\u5c0f\u8282\uff09\uff0c\u975e\u5e38\u91cd\u8981\u7684\u539f\u5219\uff0c\u5bf9\u4e8e\u7ec4\u5408\u7d22\u5f15mysql\u4f1a\u4e00\u76f4\u5411\u53f3\u5339\u914d\u76f4\u5230\u9047\u5230\u8303\u56f4\u67e5\u8be2(>\u3001<\u3001between\u3001like)\u5c31\u505c\u6b62\u5339\u914d(\u6307\u7684\u662f\u8303\u56f4\u5927\u4e86\uff0c\u6709\u7d22\u5f15\u901f\u5ea6\u4e5f\u6162)<\/strong><\/p>\n
\n
\u4f8b\u5982\r\n\u6761\u4ef6\uff1aa = 1 and b = 2 and c > 3 and d = 4 \r\n\u5e94\u8be5\u521b\u5efa\u7684\u8054\u5408\u7d22\u5f15\u662f\r\n(a,b,d,c)\uff0c\u5373\u628a\u9501\u5b9a\u8303\u56f4\u5927\u7684\u5b57\u6bb5\u5f80\u53f3\u653e\r\n\u4f9d\u636e\u7d22\u5f15\u4e0b\u63a8\u6280\u672fa,b,d\u7684\u987a\u5e8f\u662f\u53ef\u4ee5\u4efb\u610f\u8c03\u6574\u7684<\/pre>\n<\/div>\n
\"\"<\/div><\/p>\n
6\u3001\u5176\u4ed6\u60c5\u51b5\uff1a\u4e0d\u8d70\u7d22\u5f15<\/strong><\/p>\n
\n
# 1\uff09\u6ca1\u6709\u67e5\u8be2\u6761\u4ef6\uff0c\u6216\u8005\u67e5\u8be2\u6761\u4ef6\u6ca1\u6709\u7528\u5230\u7d22\u5f15\u5217\r\n\u6ca1\u6709\u67e5\u8be2\u6761\u4ef6\r\nmysql> explain select * from world.city;\r\n\r\n\u6ca1\u6709\u7528\u7d22\u5f15\u5217\u505a\u6761\u4ef6\r\nmysql> explain select * from world.city where 1=1;\r\nmysql> explain select * from world.city where name='shanghai';\r\n\r\n# 2\uff09\u67e5\u8be2\u7ed3\u679c\u96c6\u662f\u539f\u8868\u4e2d\u7684\u5927\u90e8\u5206\u6570\u636e\uff0c\u5e94\u8be5\u662f25\uff05\u4ee5\u4e0a\r\n\u5982\u679c\u751f\u4ea7\u4e2d,\u5fc5\u987b\u6709\u8fd9\u79cd\u5168\u8868\u626b\u63cf\u7684\u9700\u6c42\u4e0d\u8d70\u7d22\u5f15\r\nmysql> explain select * from world.city where population > 50;\r\n\r\n\u5982\u679c\u4e1a\u52a1\u5141\u8bb8\uff0c\u53ef\u4ee5\u4f7f\u7528limit\u63a7\u5236\uff0c\u53ef\u4ee5\u8d70\u7d22\u5f15\r\nmysql> explain select * from world.city where population>50 limit 10;\r\n\r\n\u5982\u679c\u4e1a\u52a1\u4e0d\u5141\u8bb8\uff0c\u53ef\u4ee5\u4f7f\u7528\u7f13\u5b58\r\n\u524d\u9762\u52a0\u4e0a\u7f13\u5b58,memcached,redis\r\n\r\n# 3\uff09\u7d22\u5f15\u672c\u8eab\u5931\u6548\uff0c\u7edf\u8ba1\u6570\u636e\u4e0d\u771f\u5b9e\r\n\u53cd\u590d\u4fee\u6539\uff0c\u63d2\u5165\u6570\u636e\uff0c\u7d22\u5f15\u88ab\u4fee\u6539\u574f\u4e86\uff0c\u6bcf\u6b21\u90fd\u4f1a\u8fdb\u884c\u6392\u5e8f\r\n\r\n# 4\uff09\u67e5\u8be2\u6761\u4ef6\u4f7f\u7528\u51fd\u6570\u5728\u7d22\u5f15\u5217\u4e0a\u6216\u8005\u5bf9\u7d22\u5f15\u5217\u8fdb\u884c\u8fd0\u7b97\uff0c\u8fd0\u7b97\u5305\u62ec(+\uff0c-\uff0c*\u7b49)\r\nmysql> explain select * from world.city where id=9;\r\nmysql> select * from tb1 where reverse(email) = 'egon';\r\n\r\n\u67e5\u8be2ID\u7b49\u4e8e9\u7684\u6570\u636e\uff0c\u4f1a\u5bfc\u81f4\u4e0d\u8d70\u7d22\u5f15\r\nmysql> explain select * from world.city where id-1=8;\r\n\r\n\u67e5\u8be2ID\u7b49\u4e8e9\u7684\u6570\u636e\uff0c\u53ef\u4ee5\u5728\u540e\u9762\u4f5c\u52a0\u51cf\r\nmysql> explain select * from world.city where id=8+1;\r\n\r\n# 5\uff09\u9690\u5f0f\u8f6c\u6362,\u4f1a\u5bfc\u81f4\u7d22\u5f15\u5931\u6548\r\n\u5982\u679c\u5217\u662f\u5b57\u7b26\u4e32\u7c7b\u578b\uff0c\u4f20\u5165\u6761\u4ef6\u662f\u5fc5\u987b\u7528\u5f15\u53f7\u5f15\u8d77\u6765\uff0c\u4e0d\u7136...\r\nselect * from tb1 where email = 999;\r\n\r\n\u521b\u5efa\u4e00\u4e2a\u8868\r\ncreate table test(id int, name varchar(20), phonenum varchar(10));\r\n\r\n\u63d2\u5165\u51e0\u6761\u6570\u636e\r\ninsert into test values(1,'jc','110'),(2,'xf',119),(3,'jh',120);\r\n\r\n\u5efa\u7acb\u7d22\u5f15\uff0c\u6ca1\u6709\u76f8\u540c\u503c\u53ef\u4ee5\u7ed9\u552f\u4e00\u7d22\u5f15\r\nalter table test unique key idx_num(phonenum);\r\n\r\n\u67e5\u770b\u7d22\u5f15\r\nshow index from test;\r\n\r\n\u67e5\u8be2\u8bed\u53e5\u7ea7\u522b\r\n\u4e0d\u8d70\u7d22\u5f15\r\nexplain select * from test where phonenum=110;\r\n\u8d70\u7d22\u5f15\r\nexplain select * from test where phonenum='110'; -- \u5f15\u53f7\u53ef\u80fd\u5bfc\u81f4\u5927\u4e8b\u6545\r\n\u56e0\u4e3a\u8fd9\u4e00\u5217\u662fvarchar\u7c7b\u578b\uff0c\u5fc5\u987b\u4ee5\u5b57\u7b26\u6765\u67e5\u8be2\r\n\r\n\r\n# 6\uff09<> \u548c not in  , or \u4e5f\u4e0d\u8d70\u7d22\u5f15\r\nmysql> explain select * from test where phonenum <> '120';\r\nmysql> explain select * from test where phonenum not in (120);\r\nmysql> explain select * from test where telnum='110' or telnum='119';\r\n\r\n\u4f7f\u7528union all\u53ef\u4ee5\u8d70\u7d22\u5f15\r\nmysql> explain select * from test where telnum='110' union all select * from test where telnum='119';\r\n\r\n# 7\uff09like\u6a21\u7cca\u67e5\u8be2%\u5728\u6700\u524d\u9762,\u4e0d\u8d70\u7d22\u5f15\r\n%\u5728\u524d\u9762\u4e0d\u8d70\u7d22\u5f15\r\nmysql> explain select * from city where countrycode like '%HN';\r\n\r\n%\u5728\u540e\u9762\uff0c\u8d70\u7d22\u5f15\r\nmysql> explain select * from city where countrycode like 'CH%';\r\n\r\n\u653e\u5728\u540e\u9762\u4e5f\u4e0d\u662f\u4e00\u5b9a\u4e86\uff0c\u56e0\u4e3a\u6d89\u53ca\u5230\u7b2c\u4e8c\u70b9\u7ed3\u679c\u7684\u5360\u603b\u6570\u636e\u7684\u6bd4\u4f8b\r\n\r\n%\u5728\u6700\u524d\u9762\u7684\u641c\u7d22\u9700\u6c42\uff0c\u5efa\u8bae\u4f7f\u7528elasticsearch  ES  ELK(E) \u641c\u7d22\u5f15\u64ce\u5f0f\u7684 \u6570\u636e\u5e93\r\n\r\n# 8\uff09\u5355\u72ec\u5f15\u7528\u8054\u5408\u7d22\u5f15\u91cc\u975e\u7b2c\u4e00\u4f4d\u7f6e\u7684\u7d22\u5f15\u5217\r\n\u7ec4\u5408\u7d22\u5f15\u6700\u5de6\u524d\u7f00\r\n\u5982\u679c\u7ec4\u5408\u7d22\u5f15\u4e3a\uff1a(name,email)\r\nname and email -- \u547d\u4e2d\u7d22\u5f15\r\nname -- \u547d\u4e2d\u7d22\u5f15\r\nemail -- \u672a\u547d\u4e2d\u7d22\u5f15\r\n\r\n# 9\uff09\u6392\u5e8f\u6761\u4ef6\u4e3a\u7d22\u5f15\uff0c\u5219select\u5b57\u6bb5\u5fc5\u987b\u4e5f\u662f\u7d22\u5f15\u5b57\u6bb5\uff0c\u5426\u5219\u65e0\u6cd5\u547d\u4e2d\r\n- order by\r\nselect name from s1 order by email desc;\r\n\u5f53\u6839\u636e\u7d22\u5f15\u6392\u5e8f\u65f6\u5019\uff0cselect\u67e5\u8be2\u7684\u5b57\u6bb5\u5982\u679c\u4e0d\u662f\u7d22\u5f15\uff0c\u5219\u901f\u5ea6\u4ecd\u7136\u5f88\u6162\r\nselect email from s1 order by email desc;\r\n\u7279\u522b\u7684\uff1a\u5982\u679c\u5bf9\u4e3b\u952e\u6392\u5e8f\uff0c\u5219\u8fd8\u662f\u901f\u5ea6\u5f88\u5feb\uff1a\r\nselect * from tb1 order by nid desc;<\/pre>\n<\/div>\n
\u4e8c \u603b\u7ed3\u7d22\u5f15\u4f7f\u7528\u539f\u5219<\/strong><\/p>\n
\n
- 1\u3001\u5728\u521b\u5efa\u7d22\u5f15\u7684\u65f6\u5019\uff0c\u4f1a\u628a\u8be5\u5217\u6240\u6709\u7684\u6570\u636e\u6309\u7167btree\u7684\u65b9\u5f0f\u8fdb\u884c\u6392\u5e8f\r\n\r\n- 2\u3001\u4e3a\u5e38\u4f5c\u4e3a\u67e5\u8be2\u6761\u4ef6\u7684\u5b57\u6bb5\u5efa\u7acb\u7d22\u5f15\r\n\r\n- 3\u3001\u9650\u5236\u7d22\u5f15\u7684\u6570\u76ee\uff0c\u4e0d\u8981\u6bcf\u5217\u90fd\u521b\u5efa\u7d22\u5f15\r\n\u6bcf\u4e2a\u7d22\u5f15\u90fd\u9700\u8981\u5360\u7528\u78c1\u76d8\u7a7a\u95f4\uff0c\u7d22\u5f15\u8d8a\u591a\uff0c\u9700\u8981\u7684\u78c1\u76d8\u7a7a\u95f4\u5c31\u8d8a\u5927\u3002\r\n\u4fee\u6539\u8868\u65f6\uff0c\u5bf9\u7d22\u5f15\u7684\u91cd\u6784\u548c\u66f4\u65b0\u5f88\u9ebb\u70e6\u3002\u8d8a\u591a\u7684\u7d22\u5f15\uff0c\u4f1a\u4f7f\u66f4\u65b0\u8868\u53d8\u5f97\u5f88\u6d6a\u8d39\u65f6\u95f4\u3002\r\n\r\n- 4\u3001\u5728\u540c\u4e00\u5217\u4e0a\uff0c\u5c3d\u91cf\u907f\u514d\u521b\u5efa\u591a\u4e2a\u7d22\u5f15\uff0c\u53ef\u4ee5\u521b\u5efa\u591a\u4e2a\u4f46\u662f\u5b83\u4eec\u662f\u6709\u4f18\u5148\u7ea7\u7684\uff0c\u5148\u8d70\u4e00\u4e2a\u5c31\u4e0d\u4f1a\u518d\u8d70\u53e6\u4e00\u4e2a\u7d22\u5f15\u4e86\uff1b\r\n    alter table student add index idx_name(name);\r\n    alter table country add unique key uni_name(name);\r\n\r\n- 5\u3001\u907f\u514d\u5bf9\u5927\u5217\u5efa\u7d22\u5f15\uff0c\u5728\u6570\u636e\u5f88\u957f\u7684\u5217\u4e0a\u521b\u5efa\u524d\u7f00\u7d22\u5f15\r\n\r\n- 6\u3001\u5982\u679c\u53ef\u4ee5\u521b\u5efa\u552f\u4e00\u7d22\u5f15,\u5c31\u521b\u5efa\u552f\u4e00\u7d22\u5f15(\u8be5\u5217\u7684\u6570\u636e\u4e0d\u91cd\u590d)\uff0c\u67e5\u8be2\u901f\u5ea6\u5feb\r\n\r\n- 7\u3001\u4e0d\u8981\u5bf9\u91cd\u590d\u5ea6\u9ad8\u7684\u5b57\u6bb5\u521b\u5efa\u7d22\u5f15\r\n\r\n- 8\u3001\u7d22\u5f15\u4e0d\u8981\u53c2\u4e0e\u8ba1\u7b97\r\n\r\n- 9\u3001\u4e3a\u7ecf\u5e38\u8981\u6392\u5e8f,\u5206\u7ec4,\u8054\u5408\u64cd\u4f5c\u7684\u5217,\u521b\u5efa\u8054\u5408\u7d22\u5f15\r\n\u7ecf\u5e38\u9700\u8981ORDER BY\u3001GROUP BY\u3001DISTINCT\u548cUNION\u7b49\u64cd\u4f5c\u7684\u5b57\u6bb5\uff0c\u6392\u5e8f\u64cd\u4f5c\u4f1a\u6d6a\u8d39\u5f88\u591a\u65f6\u95f4\u3002\r\n\u5982\u679c\u4e3a\u5176\u5efa\u7acb\u7d22\u5f15\uff0c\u53ef\u4ee5\u6709\u6548\u5730\u907f\u514d\u6392\u5e8f\u64cd\u4f5c\r\n\r\n- 10\u3001\u5c3d\u91cf\u4f7f\u7528\u524d\u7f00\u6765\u7d22\u5f15\r\n\u521b\u5efa\u7d22\u5f15\u7684\u65f6\u5019,\u53ef\u4ee5\u7ed9\u8be5\u5217\u6240\u6709\u6570\u636e\u8fdb\u884c\u6392\u5e8f\r\ncreate index xxxx on tb(title(19)) # text\u7c7b\u578b\uff0c\u5fc5\u987b\u5236\u5b9a\u957f\u5ea6\r\n\r\n- 11\u3001\u5220\u9664\u4e0d\u518d\u4f7f\u7528\u6216\u8005\u5f88\u5c11\u4f7f\u7528\u7684\u7d22\u5f15\r\n\u8868\u4e2d\u7684\u6570\u636e\u88ab\u5927\u91cf\u66f4\u65b0\uff0c\u6216\u8005\u6570\u636e\u7684\u4f7f\u7528\u65b9\u5f0f\u88ab\u6539\u53d8\u540e\uff0c\u539f\u6709\u7684\u4e00\u4e9b\u7d22\u5f15\u53ef\u80fd\u4e0d\u518d\u9700\u8981\u3002\u6570\u636e\u5e93\u7ba1\u7406\u5458\u5e94\u5f53\u5b9a\u671f\u627e\u51fa\u8fd9\u4e9b\u7d22\u5f15\uff0c\u5c06\u5b83\u4eec\u5220\u9664\uff0c\u4ece\u800c\u51cf\u5c11\u7d22\u5f15\u5bf9\u66f4\u65b0\u64cd\u4f5c\u7684\u5f71\u54cd\u3002\r\n\r\n- 12\u3001\u907f\u514d\u4f7f\u7528select *\r\n\r\n- 13\u3001count(1)\u6216count(\u5217) \u4ee3\u66ff count(*)\uff0cps\uff1amysql\u4e2d\u6ca1\u6709\u5dee\u522b\u4e86\r\n\r\n- 14\u3001\u521b\u5efa\u8868\u65f6\u5c3d\u91cf\u65f6 varchar \u4ee3\u66ff char\r\n\r\n- 15\u3001\u8868\u7684\u5b57\u6bb5\u987a\u5e8f\u56fa\u5b9a\u957f\u5ea6\u7684\u5b57\u6bb5\u4f18\u5148\r\n\r\n- 16\u3001\u4f7f\u7528\u8fde\u63a5\uff08JOIN\uff09\u6765\u4ee3\u66ff\u5b50\u67e5\u8be2(Sub-Queries)\r\n\r\n- 17\u3001\u8fde\u8868\u65f6\u6ce8\u610f\u6761\u4ef6\u7c7b\u578b\u9700\u4e00\u81f4<\/pre>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
\u4e00 \u7d22\u5f15\u547d\u4e2d\u4e5f\u672a\u5fc5\u4f1a\u52a0\u901f \u5e76\u4e0d\u662f\u8bf4\u6211\u4eec\u521b\u5efa\u4e86\u7d22\u5f15\u5c31\u4e00\u5b9a\u4f1a\u52a0\u5feb\u67e5\u8be2\u901f\u5ea6\uff0c\u82e5\u60f3\u5229\u7528\u7d22\u5f15\u8fbe\u5230\u9884\u60f3\u7684\u63d0\u9ad8\u67e5\u8be2\u901f\u5ea6\u7684\u6548\u679c […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/11461"}],"collection":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=11461"}],"version-history":[{"count":12,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/11461\/revisions"}],"predecessor-version":[{"id":11485,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/11461\/revisions\/11485"}],"wp:attachment":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=11461"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=11461"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=11461"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}