{"id":207,"date":"2021-08-16T23:45:42","date_gmt":"2021-08-16T15:45:42","guid":{"rendered":"http:\/\/www.cgh0610.cn\/?p=207"},"modified":"2021-08-17T00:54:36","modified_gmt":"2021-08-16T16:54:36","slug":"mysql%e6%89%a7%e8%a1%8c%e8%bf%87%e7%a8%8b%e3%80%81%e6%89%a7%e8%a1%8c%e9%a1%ba%e5%ba%8f%e3%80%81%e6%89%a7%e8%a1%8c%e8%ae%a1%e5%88%92","status":"publish","type":"post","link":"https:\/\/www.cgh0610.cn\/?p=207","title":{"rendered":"MySql\u6267\u884c\u8fc7\u7a0b\u3001\u6267\u884c\u987a\u5e8f\u3001\u6267\u884c\u8ba1\u5212"},"content":{"rendered":"<p>\u524d\u8a00\uff1aMySql\u662f\u6211\u4eec\u5e73\u5e38\u7528\u7684\u6bd4\u8f83\u591a\u7684\u6570\u636e\u5e93\uff0c\u4f46\u662f\u65f6\u95f4\u4e45\u4e86\u540e\u603b\u4f1a\u6216\u591a\u6216\u5c11\u5fd8\u8bb0\u4e86\u4e00\u6761sql\u5b8c\u6574\u7684\u6267\u884c\u8fc7\u7a0b\uff0c\u4eca\u5929\u67e5\u8d44\u6599\uff0c\u91cd\u65b0\u7406\u89e3\u4e86\u4e00\u4e0bMySql\u8bed\u53e5\u6267\u884c\u7684\u5168\u8fc7\u7a0b\u3002<\/p>\n<p>\u5bfc\u5f15\uff1a<br \/>\n\u4e00\u3001\u6267\u884c\u8fc7\u7a0b<br \/>\n\u4e8c\u3001\u6267\u884c\u8fc7\u7a0b\u4e2d\u7684\u72b6\u6001<br \/>\n\u4e09\u3001\u6267\u884c\u7684\u987a\u5e8f<br \/>\n\u56db\u3001\u6267\u884c\u7684\u8ba1\u5212<br \/>\n\u4e94\u3001EXPLAIN\u7684\u5c40\u9650<br \/>\n\u516d\u3001\u603b\u7ed3<\/p>\n<h2>\u4e00\u3001\u6267\u884c\u8fc7\u7a0b<\/h2>\n<p>MySql\u6574\u4f53\u7684\u6267\u884c\u8fc7\u7a0b\u5982\u4e0b\u56fe\u6240\u793a:<br \/>\n<a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/1066538-20201016015745814-1815633939.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/1066538-20201016015745814-1815633939.png\" alt=\"\" \/><\/a><\/p>\n<h3>1.1:\u8fde\u63a5\u5668<\/h3>\n<p>\u8fde\u63a5\u5668\u7684\u4e3b\u8981\u804c\u8d23\u5c31\u662f:<\/p>\n<p>\u2460\u8d1f\u8d23\u4e0e\u5ba2\u6237\u7aef\u7684\u901a\u4fe1,\u662f\u534a\u53cc\u5de5\u6a21\u5f0f,\u8fd9\u5c31\u610f\u5473\u7740\u67d0\u4e00\u56fa\u5b9a\u65f6\u523b\u53ea\u80fd\u7531\u5ba2\u6237\u7aef\u5411\u670d\u52a1\u5668\u8bf7\u6c42\u6216\u8005\u670d\u52a1\u5668\u5411\u5ba2\u6237\u7aef\u53d1\u9001\u6570\u636e,\u800c\u4e0d\u80fd\u540c\u65f6\u8fdb\u884c\uff0c\u5373\u540c\u4e00\u65f6\u95f4\u53ea\u80fd\u8fdb\u884c\u4e00\u4e2a\u52a8\u4f5c<\/p>\n<p>\u2461\u9a8c\u8bc1\u8bf7\u6c42\u7528\u6237\u7684\u8d26\u6237\u548c\u5bc6\u7801\u662f\u5426\u6b63\u786e,\u5982\u679c\u8d26\u6237\u548c\u5bc6\u7801\u9519\u8bef,\u4f1a\u62a5\u9519:Access denied for user &#8216;root&#8217;@&#8217;localhost&#8217; (using password: YES)<\/p>\n<p>\u2462\u5982\u679c\u7528\u6237\u7684\u8d26\u6237\u548c\u5bc6\u7801\u9a8c\u8bc1\u901a\u8fc7,\u4f1a\u5728mysql\u81ea\u5e26\u7684\u6743\u9650\u8868\u4e2d\u67e5\u8be2\u5f53\u524d\u7528\u6237\u7684\u6743\u9650:<\/p>\n<p>mysql\u4e2d\u5b58\u57284\u4e2a\u63a7\u5236\u6743\u9650\u7684\u8868\uff0c\u5206\u522b\u4e3auser\u8868\uff0cdb\u8868\uff0ctables_priv\u8868\uff0ccolumns_priv\u8868,mysql\u6743\u9650\u8868\u7684\u9a8c\u8bc1\u8fc7\u7a0b\u4e3a\uff1a<\/p>\n<p>1:User\u8868:\u5b58\u653e\u7528\u6237\u8d26\u6237\u4fe1\u606f\u4ee5\u53ca\u5168\u5c40\u7ea7\u522b\uff08\u6240\u6709\u6570\u636e\u5e93\uff09\u6743\u9650\uff0c\u51b3\u5b9a\u4e86\u6765\u81ea\u54ea\u4e9b\u4e3b\u673a\u7684\u54ea\u4e9b\u7528\u6237\u53ef\u4ee5\u8bbf\u95ee\u6570\u636e\u5e93\u5b9e\u4f8b\uff1b<br \/>\nDb\u8868:\u5b58\u653e\u6570\u636e\u5e93\u7ea7\u522b\u7684\u6743\u9650\uff0c\u51b3\u5b9a\u4e86\u6765\u81ea\u54ea\u4e9b\u4e3b\u673a\u7684\u54ea\u4e9b\u7528\u6237\u53ef\u4ee5\u8bbf\u95ee\u6b64\u6570\u636e\u5e93\uff1b<br \/>\nTables_priv\u8868\uff1a\u5b58\u653e\u8868\u7ea7\u522b\u7684\u6743\u9650\uff0c\u51b3\u5b9a\u4e86\u6765\u81ea\u54ea\u4e9b\u4e3b\u673a\u7684\u54ea\u4e9b\u7528\u6237\u53ef\u4ee5\u8bbf\u95ee\u6570\u636e\u5e93\u7684\u8fd9\u4e2a\u8868\uff1b<br \/>\nColumns_priv\u8868\uff1a\u5b58\u653e\u5217\u7ea7\u522b\u7684\u6743\u9650\uff0c\u51b3\u5b9a\u4e86\u6765\u81ea\u54ea\u4e9b\u4e3b\u673a\u7684\u54ea\u4e9b\u7528\u6237\u53ef\u4ee5\u8bbf\u95ee\u6570\u636e\u5e93\u8868\u7684\u8fd9\u4e2a\u5b57\u6bb5\uff1b<br \/>\nProcs_priv\u8868\uff1a\u5b58\u653e\u5b58\u50a8\u8fc7\u7a0b\u548c\u51fd\u6570\u7ea7\u522b\u7684\u6743\u9650\u3002<\/p>\n<p>2:\u5148\u4eceuser\u8868\u4e2d\u7684Host,User,Password\u8fd93\u4e2a\u5b57\u6bb5\u4e2d\u5224\u65ad\u8fde\u63a5\u7684ip\u3001\u7528\u6237\u540d\u3001\u5bc6\u7801\u662f\u5426\u5b58\u5728\uff0c\u5b58\u5728\u5219\u901a\u8fc7\u9a8c\u8bc1\u3002<\/p>\n<p>3:\u901a\u8fc7\u8eab\u4efd\u8ba4\u8bc1\u540e\uff0c\u8fdb\u884c\u6743\u9650\u5206\u914d\uff0c\u6309\u7167user\uff0cdb\uff0ctables_priv\uff0ccolumns_priv\u7684\u987a\u5e8f\u8fdb\u884c\u9a8c\u8bc1\u3002\u5373\u5148\u68c0\u67e5\u5168\u5c40\u6743\u9650\u8868user\uff0c\u5982\u679cuser\u4e2d\u5bf9\u5e94\u7684\u6743\u9650\u4e3aY\uff0c\u5219\u6b64\u7528\u6237\u5bf9\u6240\u6709\u6570\u636e\u5e93\u7684\u6743\u9650\u90fd\u4e3aY\uff0c\u5c06\u4e0d\u518d\u68c0\u67e5db, tables_priv,columns_priv\uff1b\u5982\u679c\u4e3aN\uff0c\u5219\u5230db\u8868\u4e2d\u68c0\u67e5\u6b64\u7528\u6237\u5bf9\u5e94\u7684\u5177\u4f53\u6570\u636e\u5e93\uff0c\u5e76\u5f97\u5230db\u4e2d\u4e3aY\u7684\u6743\u9650\uff1b\u5982\u679cdb\u4e2d\u4e3aN\uff0c\u5219\u68c0\u67e5tables_priv\u4e2d\u6b64\u6570\u636e\u5e93\u5bf9\u5e94\u7684\u5177\u4f53\u8868\uff0c\u53d6\u5f97\u8868\u4e2d\u7684\u6743\u9650Y\uff0c\u4ee5\u6b64\u7c7b\u63a8<\/p>\n<p>4:\u5982\u679c\u5728\u4efb\u4f55\u4e00\u4e2a\u8fc7\u7a0b\u4e2d\u6743\u9650\u9a8c\u8bc1\u4e0d\u901a\u8fc7,\u90fd\u4f1a\u62a5\u9519<\/p>\n<h3>1.2:\u7f13\u5b58<\/h3>\n<p>mysql\u7684\u7f13\u5b58\u4e3b\u8981\u7684\u4f5c\u7528\u662f\u4e3a\u4e86\u63d0\u5347\u67e5\u8be2\u7684\u6548\u7387\uff0c\u7f13\u5b58\u4ee5key\u548cvalue\u7684\u54c8\u5e0c\u8868\u5f62\u5f0f\u5b58\u50a8\uff0ckey\u662f\u5177\u4f53\u7684sql\u8bed\u53e5\uff0cvalue\u662f\u7ed3\u679c\u7684\u96c6\u5408\u3002\u5982\u679c\u65e0\u6cd5\u547d\u4e2d\u7f13\u5b58,\u5c31\u7ee7\u7eed\u8d70\u5230\u5206\u6790\u5668\u7684\u7684\u4e00\u6b65,\u5982\u679c\u547d\u4e2d\u7f13\u5b58\u5c31\u76f4\u63a5\u8fd4\u56de\u7ed9\u5ba2\u6237\u7aef \u3002\u4e0d\u8fc7\u9700\u8981\u6ce8\u610f\u7684\u662f\u5728mysql\u76848.0\u7248\u672c\u4ee5\u540e\uff0c\u7f13\u5b58\u88ab\u5b98\u65b9\u5220\u9664\u6389\u4e86\u3002\u4e4b\u6240\u4ee5\u5220\u9664\u6389,\u662f\u56e0\u4e3a\u67e5\u8be2\u7f13\u5b58\u7684\u5931\u6548\u975e\u5e38\u9891\u7e41,\u5982\u679c\u5728\u4e00\u4e2a\u5199\u591a\u8bfb\u5c11\u7684\u73af\u5883\u4e2d,\u7f13\u5b58\u4f1a\u9891\u7e41\u7684\u65b0\u589e\u548c\u5931\u6548\u3002\u5bf9\u4e8e\u67d0\u4e9b\u66f4\u65b0\u538b\u529b\u5927\u7684\u6570\u636e\u5e93\u6765\u8bf4\uff0c\u67e5\u8be2\u7f13\u5b58\u7684\u547d\u4e2d\u7387\u4f1a\u975e\u5e38\u4f4e,mysql\u4e3a\u4e86\u7ef4\u62a4\u7f13\u5b58\u53ef\u80fd\u4f1a\u51fa\u73b0\u4e00\u5b9a\u7684\u4f38\u7f29\u6027\u7684\u95ee\u9898,\u76ee\u524d\u57285.6\u7684\u7248\u672c\u4e2d\u5df2\u7ecf\u9ed8\u8ba4\u5173\u95ed\u4e86\uff0c\u6bd4\u8f83\u63a8\u8350\u7684\u4e00\u79cd\u505a\u6cd5\u662f\u5c06\u7f13\u5b58\u653e\u5728\u5ba2\u6237\u7aef\uff0c\u6027\u80fd\u5927\u6982\u4f1a\u63d0\u53475\u500d\u5de6\u53f3\u3002<\/p>\n<h3>1.3:\u5206\u6790\u5668<\/h3>\n<p>\u5206\u6790\u5668\u7684\u4e3b\u8981\u4f5c\u7528\u662f\u5c06\u5ba2\u6237\u7aef\u53d1\u8fc7\u6765\u7684sql\u8bed\u53e5\u8fdb\u884c\u5206\u6790\uff0c\u8fd9\u5c06\u5305\u62ec\u9884\u5904\u7406\u4e0e\u89e3\u6790\u8fc7\u7a0b\uff0c\u5728\u8fd9\u4e2a\u9636\u6bb5\u4f1a\u89e3\u6790sql\u8bed\u53e5\u7684\u8bed\u4e49\uff0c\u5e76\u8fdb\u884c\u5173\u952e\u8bcd\u548c\u975e\u5173\u952e\u8bcd\u8fdb\u884c\u63d0\u53d6\u3001\u89e3\u6790\uff0c\u5e76\u7ec4\u6210\u4e00\u4e2a\u89e3\u6790\u6811\u3002\u5177\u4f53\u7684\u5173\u952e\u8bcd\u5305\u62ec\u4e0d\u9650\u5b9a\u4e8e\u4ee5\u4e0b\uff1aselect\/update\/delete\/or\/in\/where\/group by\/having\/count\/limit\u7b49.\u5982\u679c\u5206\u6790\u5230\u8bed\u6cd5\u9519\u8bef\uff0c\u4f1a\u76f4\u63a5\u7ed9\u5ba2\u6237\u7aef\u629b\u51fa\u5f02\u5e38:ERROR:You have an error in your SQL syntax.<\/p>\n<p>\u6bd4\u5982\uff1aselect *  from user where userId =1234;<\/p>\n<p>\u5728\u5206\u6790\u5668\u4e2d\u5c31\u901a\u8fc7\u8bed\u4e49\u89c4\u5219\u5668\u5c06select from where\u8fd9\u4e9b\u5173\u952e\u8bcd\u63d0\u53d6\u548c\u5339\u914d\u51fa\u6765,mysql\u4f1a\u81ea\u52a8\u5224\u65ad\u5173\u952e\u8bcd\u548c\u975e\u5173\u952e\u8bcd\uff0c\u5c06\u7528\u6237\u7684\u5339\u914d\u5b57\u6bb5\u548c\u81ea\u5b9a\u4e49\u8bed\u53e5\u8bc6\u522b\u51fa\u6765\u3002\u8fd9\u4e2a\u9636\u6bb5\u4e5f\u4f1a\u505a\u4e00\u4e9b\u6821\u9a8c:\u6bd4\u5982\u6821\u9a8c\u5f53\u524d\u6570\u636e\u5e93\u662f\u5426\u5b58\u5728user\u8868\uff0c\u540c\u65f6\u5047\u5982User\u8868\u4e2d\u4e0d\u5b58\u5728userId\u8fd9\u4e2a\u5b57\u6bb5\u540c\u6837\u4f1a\u62a5\u9519\uff1aunknown column in field list.<\/p>\n<h3>1.4:\u4f18\u5316\u5668<\/h3>\n<p>\u80fd\u591f\u8fdb\u5165\u5230\u4f18\u5316\u5668\u9636\u6bb5\u8868\u793asql\u662f\u7b26\u5408mysql\u7684\u6807\u51c6\u8bed\u4e49\u89c4\u5219\u7684\u5e76\u4e14\u53ef\u4ee5\u6267\u884c\u7684\uff0c\u6b64\u9636\u6bb5\u4e3b\u8981\u662f\u8fdb\u884csql\u8bed\u53e5\u7684\u4f18\u5316\uff0c\u4f1a\u6839\u636e\u6267\u884c\u8ba1\u5212\u8fdb\u884c\u6700\u4f18\u7684\u9009\u62e9,\u5339\u914d\u5408\u9002\u7684\u7d22\u5f15,\u9009\u62e9\u6700\u4f73\u7684\u6267\u884c\u65b9\u6848\u3002\u6bd4\u5982\u4e00\u4e2a\u5178\u578b\u7684\u4f8b\u5b50\u662f\u8fd9\u6837\u7684\uff1a<\/p>\n<p>\u8868T,\u5bf9A\u3001B\u3001C\u5217\u5efa\u7acb\u8054\u5408\u7d22\u5f15\uff0c\u5728\u8fdb\u884c\u67e5\u8be2\u7684\u65f6\u5019\uff0c\u5f53sql\u67e5\u8be2\u5230\u7684\u7ed3\u679c\u662f:select xx where  B=x and A=x and C=x.\u5f88\u591a\u4eba\u4f1a\u4ee5\u4e3a\u662f\u7528\u4e0d\u5230\u7d22\u5f15\u7684\uff0c\u4f46\u5176\u5b9e\u4f1a\u7528\u5230,\u867d\u7136\u7d22\u5f15\u5fc5\u987b\u7b26\u5408\u6700\u5de6\u539f\u5219\u624d\u80fd\u4f7f\u7528,\u4f46\u662f\u672c\u8d28\u4e0a,\u4f18\u5316\u5668\u4f1a\u81ea\u52a8\u5c06\u8fd9\u6761sql\u4f18\u5316\u4e3a:where A=x and B=x and C=X,\u8fd9\u79cd\u4f18\u5316\u4f1a\u4e3a\u4e86\u5e95\u5c42\u80fd\u591f\u5339\u914d\u5230\u7d22\u5f15\uff0c\u540c\u65f6\u5728\u8fd9\u4e2a\u9636\u6bb5\u662f\u81ea\u52a8\u6309\u7167\u6267\u884c\u8ba1\u5212\u8fdb\u884c\u9884\u5904\u7406,mysql\u4f1a\u8ba1\u7b97\u5404\u4e2a\u6267\u884c\u65b9\u6cd5\u7684\u6700\u4f73\u65f6\u95f4,\u6700\u7ec8\u786e\u5b9a\u4e00\u6761\u6267\u884c\u7684sql\u4ea4\u7ed9\u6700\u540e\u7684\u6267\u884c\u5668\u3002<\/p>\n<h3>1.5:\u6267\u884c\u5668<\/h3>\n<p>\u5728\u6267\u884c\u5668\u7684\u9636\u6bb5,\u6b64\u65f6\u4f1a\u8c03\u7528\u5b58\u50a8\u5f15\u64ce\u7684API,API\u4f1a\u8c03\u7528\u5b58\u50a8\u5f15\u64ce\uff0c\u4e3b\u8981\u6709\u4e00\u4e0b\u5b58\u50a8\u7684\u5f15\u64ce\uff0c\u4e0d\u8fc7\u5e38\u7528\u7684\u8fd8\u662fmyisam\u548cinnodb:<br \/>\n <a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u5f15\u64ce.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u5f15\u64ce.png\" alt=\"\" \/><\/a><br \/>\n \u5f15\u64ce\u4ee5\u524d\u7684\u540d\u5b57\u53eb\u505a:\u8868\u5904\u7406\u5668(\u66f4\u76f4\u89c2)\u8d1f\u8d23\u5bf9\u5177\u4f53\u7684\u6570\u636e\u6587\u4ef6\u8fdb\u884c\u64cd\u4f5c,\u5bf9sql\u7684\u8bed\u4e49\u6bd4\u5982select\u6216\u8005update\u8fdb\u884c\u5206\u6790,\u6267\u884c\u5177\u4f53\u7684\u64cd\u4f5c\u3002\u5728\u6267\u884c\u5b8c\u4ee5\u540e\u4f1a\u5c06\u5177\u4f53\u7684\u64cd\u4f5c\u8bb0\u5f55\u5230binlog\u4e2d,\u9700\u8981\u6ce8\u610f\u7684\u4e00\u70b9\u662f:select\u4e0d\u4f1a\u8bb0\u5f55\u5230binlog\u4e2d,\u53ea\u6709update\/delete\/insert\u624d\u4f1a\u8bb0\u5f55\u5230binlog\u4e2d\u3002\u800cupdate\u4f1a\u91c7\u7528\u4e24\u9636\u6bb5\u63d0\u4ea4\u7684\u65b9\u5f0f,\u8bb0\u5f55\u90fdredolog\u4e2d\u3002<\/p>\n<h2>\u4e8c\u3001\u6267\u884c\u8fc7\u7a0b\u4e2d\u7684\u72b6\u6001<\/h2>\n<p>\u53ef\u4ee5\u901a\u8fc7\u547d\u4ee4:show full processlist,\u5c55\u793a\u6240\u6709\u7684\u5904\u7406\u8fdb\u7a0b,\u4e3b\u8981\u5305\u542b\u4e86\u4ee5\u4e0b\u7684\u72b6\u6001\uff0c\u8868\u793a\u670d\u52a1\u5668\u5904\u7406\u5ba2\u6237\u7aef\u7684\u72b6\u6001\uff0c\u72b6\u6001\u5305\u542b\u4e86\u4ece\u5ba2\u6237\u7aef\u53d1\u8d77\u8bf7\u6c42\u5230\u540e\u53f0\u670d\u52a1\u5668\u5904\u7406\u7684\u8fc7\u7a0b\uff0c\u5305\u62ec\u52a0\u9501\u7684\u8fc7\u7a0b\u3001\u7edf\u8ba1\u5b58\u50a8\u5f15\u64ce\u7684\u4fe1\u606f\uff0c\u6392\u5e8f\u6570\u636e\u3001\u641c\u7d22\u4e2d\u95f4\u8868\u3001\u53d1\u9001\u6570\u636e\u7b49\u3002\u56ca\u62ec\u4e86\u6240\u6709\u7684mysql\u7684\u6240\u6709\u72b6\u6001,\u5176\u4e2d\u5177\u4f53\u7684\u542b\u4e49\u5982\u4e0b\u56fe<br \/>\n<a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8fc7\u7a0b\u72b6\u6001.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8fc7\u7a0b\u72b6\u6001.png\" alt=\"\" \/><\/a><\/p>\n<h2>\u4e09\u3001\u6267\u884c\u7684\u987a\u5e8f<\/h2>\n<p>\u4e8b\u5b9e\u4e0a,sql\u5e76\u4e0d\u662f\u6309\u7167\u6211\u4eec\u7684\u4e66\u5199\u987a\u5e8f\u6765\u4ece\u524d\u5f80\u540e\u3001\u5de6\u5f80\u53f3\u4f9d\u6b21\u6267\u884c\u7684,\u5b83\u662f\u6309\u7167\u56fa\u5b9a\u7684\u987a\u5e8f\u89e3\u6790\u7684,\u4e3b\u8981\u7684\u4f5c\u7528\u5c31\u662f\u4ece\u4e0a\u4e00\u4e2a\u9636\u6bb5\u7684\u6267\u884c\u8fd4\u56de\u7ed3\u679c\u6765\u63d0\u4f9b\u7ed9\u4e0b\u4e00\u9636\u6bb5\u4f7f\u7528\uff0csql\u5728\u6267\u884c\u7684\u8fc7\u7a0b\u4e2d\u4f1a\u6709\u4e0d\u540c\u7684\u4e34\u65f6\u4e2d\u95f4\u8868\uff0c\u4e00\u822c\u662f\u6309\u7167\u5982\u4e0b\u987a\u5e8f\uff1a<br \/>\n\u4f8b\u5b50:<br \/>\n<code>select distinct s.id  from T t join  S s on t.id=s.id where t.name=\"Yrion\" group by t.mobile having count(*)&gt;2  order by s.create_time limit 5;<\/code><\/p>\n<h3>3.1:from<\/h3>\n<p>\u7b2c\u4e00\u6b65\u5c31\u662f\u9009\u62e9\u51fafrom\u5173\u952e\u8bcd\u540e\u9762\u8ddf\u7684\u8868,\u8fd9\u4e5f\u662fsql\u6267\u884c\u7684\u7b2c\u4e00\u6b65:\u8868\u793a\u8981\u4ece\u6570\u636e\u5e93\u4e2d\u6267\u884c\u54ea\u5f20\u8868\u3002<\/p>\n<p>\u5b9e\u4f8b\u8bf4\u660e:\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\u5c31\u662f\u9996\u5148\u4ece\u6570\u636e\u5e93\u4e2d\u627e\u5230\u8868T<\/p>\n<h3>3.2:join on<\/h3>\n<p>join\u662f\u8868\u793a\u8981\u5173\u8054\u7684\u8868\uff0con\u662f\u8fde\u63a5\u7684\u6761\u4ef6\uff0c\u5148\u901a\u8fc7join\u786e\u8ba4\u8981\u5173\u8054\u7684\u8868\uff0c\u518d\u901a\u8fc7on\u786e\u8ba4\u5173\u8054\u6761\u4ef6\u3002\u901a\u8fc7from\u548cjoin on\u9009\u62e9\u51fa\u9700\u8981\u6267\u884c\u7684\u6570\u636e\u5e93\u8868T\u548cS,\u4ea7\u751f\u7b1b\u5361\u5c14\u79ef,\u751f\u6210T\u548cS\u5408\u5e76\u7684\u4e34\u65f6\u4e2d\u95f4\u8868Temp1\u3002on:\u786e\u5b9a\u8868\u7684\u7ed1\u5b9a\u5173\u7cfb,\u901a\u8fc7on\u4ea7\u751f\u4e34\u65f6\u4e2d\u95f4\u8868Temp2\u3002<\/p>\n<p>\u5b9e\u4f8b\u8bf4\u660e\uff1a\u627e\u5230\u8868S,\u751f\u6210\u4e34\u65f6\u4e2d\u95f4\u8868Temp1,\u7136\u540e\u627e\u5230\u8868T\u7684id\u548cS\u7684id\u76f8\u540c\u7684\u90e8\u5206\u7ec4\u6210\u6210\u8868Temp2,Temp2\u91cc\u9762\u5305\u542b\u7740T\u548cSid\u76f8\u7b49\u7684\u6240\u6709\u6570\u636e\u3002<\/p>\n<h3>3.3:where<\/h3>\n<p>where\u8868\u793a\u7b5b\u9009,\u6839\u636ewhere\u540e\u9762\u7684\u6761\u4ef6\u8fdb\u884c\u8fc7\u6ee4,\u6309\u7167\u6307\u5b9a\u7684\u5b57\u6bb5\u7684\u503c(\u5982\u679c\u6709and\u8fde\u63a5\u7b26\u4f1a\u8fdb\u884c\u8054\u5408\u7b5b\u9009)\u4ece\u4e34\u65f6\u4e2d\u95f4\u8868Temp2\u4e2d\u7b5b\u9009\u9700\u8981\u7684\u6570\u636e,\u6ce8\u610f\u5982\u679c\u5728\u6b64\u9636\u6bb5\u627e\u4e0d\u5230\u6570\u636e\uff0c\u4f1a\u76f4\u63a5\u8fd4\u56de\u5ba2\u6237\u7aef,\u4e0d\u4f1a\u5f80\u4e0b\u8fdb\u884c.\u8fd9\u4e2a\u8fc7\u7a0b\u4f1a\u751f\u6210\u4e00\u4e2a\u4e34\u65f6\u4e2d\u95f4\u8868Temp3\u3002\u6ce8\u610f\u5728where\u4e2d\u4e0d\u53ef\u4ee5\u4f7f\u7528\u805a\u5408\u51fd\u6570\uff0c\u805a\u5408\u51fd\u6570\u4e3b\u8981\u662f(min\\max\\count\\sum\u7b49\u51fd\u6570)\u3002<\/p>\n<p>\u5b9e\u4f8b\u8bf4\u660e:\u5728temp2\u4e34\u65f6\u8868\u96c6\u5408\u4e2d\u627e\u5230T\u8868\u7684name=&#8221;Yrion&#8221;\u7684\u6570\u636e,\u627e\u5230\u6570\u636e\u540e\u4f1a\u6210\u4e34\u65f6\u4e2d\u95f4\u8868Temp3,temp3\u91cc\u5305\u542bname\u5217\u4e3a&#8221;Yrion&#8221;\u7684\u6240\u6709\u8868\u6570\u636e\u3002<\/p>\n<h3>3.4:group by<\/h3>\n<p>group by\u662f\u8fdb\u884c\u5206\u7ec4\uff0c\u5bf9where\u6761\u4ef6\u8fc7\u6ee4\u540e\u7684\u4e34\u65f6\u8868Temp3\u6309\u7167\u56fa\u5b9a\u7684\u5b57\u6bb5\u8fdb\u884c\u5206\u7ec4,\u4ea7\u751f\u4e34\u65f6\u4e2d\u95f4\u8868Temp4\uff0c\u8fd9\u4e2a\u8fc7\u7a0b\u53ea\u662f\u6570\u636e\u7684\u987a\u5e8f\u53d1\u751f\u6539\u53d8,\u800c\u6570\u636e\u603b\u91cf\u4e0d\u4f1a\u53d8\u5316,\u8868\u4e2d\u7684\u6570\u636e\u4ee5\u7ec4\u7684\u5f62\u5f0f\u5b58\u5728\u3002<\/p>\n<p>\u5b9e\u4f8b\u8bf4\u660e:\u5728temp3\u8868\u6570\u636e\u4e2d\u5bf9mobile\u8fdb\u884c\u5206\u7ec4,\u67e5\u627e\u51famobile\u4e00\u6837\u7684\u6570\u636e,\u7136\u540e\u653e\u5230\u4e00\u8d77\uff0c\u4ea7\u751ftemp4\u4e34\u65f6\u8868\u3002<\/p>\n<h3>3.5:Having<\/h3>\n<p>\u5bf9\u4e34\u65f6\u4e2d\u95f4\u8868Temp4\u8fdb\u884c\u805a\u5408,\u8fd9\u91cc\u53ef\u4ee5\u4e3acount\u7b49\u8ba1\u6570\uff0c\u7136\u540e\u4ea7\u751f\u4e2d\u95f4\u8868Temp5\uff0c\u5728\u6b64\u9636\u6bb5\u53ef\u4ee5\u4f7f\u7528select\u4e2d\u7684\u522b\u540d\u3002<\/p>\n<p>\u5b9e\u4f8b\u8bf4\u660e:\u5728temp4\u4e34\u65f6\u8868\u4e2d\u627e\u51fa\u6761\u6570\u5927\u4e8e2\u7684\u6570\u636e,\u5982\u679c\u5c0f\u4e8e2\u76f4\u63a5\u88ab\u820d\u5f03\u6389\uff0c\u7136\u540e\u751f\u6210\u4e34\u65f6\u4e2d\u95f4\u8868temp5<\/p>\n<h3>3.6:select<\/h3>\n<p>\u5bf9\u5206\u7ec4\u805a\u5408\u5b8c\u7684\u8868\u6311\u9009\u51fa\u9700\u8981\u67e5\u8be2\u7684\u6570\u636e,\u5982\u679c\u4e3a*\u4f1a\u89e3\u6790\u4e3a\u6240\u6709\u6570\u636e,\u6b64\u65f6\u4f1a\u4ea7\u751f\u4e2d\u95f4\u8868Temp6<\/p>\n<p>\u5b9e\u4f8b\u8bf4\u660e\uff1a\u5728\u6b64\u9636\u6bb5\u5c31\u662f\u5bf9temp5\u4e34\u65f6\u805a\u5408\u8868\u4e2dS\u8868\u4e2d\u7684id\u8fdb\u884c\u7b5b\u9009\u4ea7\u751fTemp6,\u6b64\u65f6temp6\u5c31\u53ea\u5305\u542b\u6709s\u8868\u7684id\u5217\u6570\u636e,\u5e76\u4e14name=&#8221;Yrion&#8221;\uff0c\u901a\u8fc7mobile\u5206\u7ec4\u6570\u91cf\u5927\u4e8e2\u7684\u6570\u636e\u3002<\/p>\n<h3>3.7:Distinct<\/h3>\n<p>distinct\u5bf9\u6240\u6709\u7684\u6570\u636e\u8fdb\u884c\u53bb\u91cd,\u6b64\u65f6\u5982\u679c\u6709min\u3001max\u51fd\u6570\u4f1a\u6267\u884c\u5b57\u6bb5\u51fd\u6570\u8ba1\u7b97\uff0c\u7136\u540e\u4ea7\u751f\u4e34\u65f6\u8868Temp7\u3002<\/p>\n<p>\u5b9e\u4f8b\u8bf4\u660e:\u6b64\u9636\u6bb5\u5bf9temp5\u4e2d\u7684\u6570\u636e\u8fdb\u884c\u53bb\u91cd,\u5f15\u64ceAPI\u4f1a\u8c03\u7528\u53bb\u91cd\u51fd\u6570\u8fdb\u884c\u6570\u636e\u7684\u8fc7\u6ee4,\u6700\u7ec8\u53ea\u4fdd\u7559id\u7b2c\u4e00\u6b21\u51fa\u73b0\u7684\u90a3\u6761\u6570\u636e,\u7136\u540e\u4ea7\u751f\u4e34\u65f6\u4e2d\u95f4\u8868temp7\u3002<\/p>\n<h3>3.8:order by<\/h3>\n<p>\u4f1a\u6839\u636eTemp7\u8fdb\u884c\u987a\u5e8f\u6392\u5217\u6216\u8005\u9006\u5e8f\u6392\u5217\uff0c\u7136\u540e\u63d2\u5165\u4e34\u65f6\u4e2d\u95f4\u8868Temp8\uff0c\u8fd9\u4e2a\u8fc7\u7a0b\u6bd4\u8f83\u8017\u8d39\u8d44\u6e90\u3002<\/p>\n<p>\u5b9e\u4f8b\u8bf4\u660e\uff1a\u8fd9\u6bb5\u4f1a\u5c06\u6240\u6709temp7\u4e34\u65f6\u8868\u4e2d\u7684\u6570\u636e\u6309\u7167\u521b\u5efa\u65f6\u95f4(create_time)\u8fdb\u884c\u6392\u5e8f,\u8fd9\u4e2a\u8fc7\u7a0b\u4e5f\u4e0d\u4f1a\u6709\u5217\u6216\u8005\u884c\u635f\u5931\u3002<\/p>\n<h3>3.9:limit<\/h3>\n<p>limit\u5bf9\u4e2d\u95f4\u8868Temp8\u8fdb\u884c\u5206\u9875,\u4ea7\u751f\u4e34\u65f6\u4e2d\u95f4\u8868Temp9,\u8fd4\u56de\u7ed9\u5ba2\u6237\u7aef\u3002<\/p>\n<p>\u5b9e\u4f8b\u8bf4\u660e:\u5728temp7\u4e2d\u6392\u597d\u5e8f\u7684\u6570\u636e,\u7136\u540e\u53d6\u524d\u4e94\u6761\u63d2\u5165\u5230Temp9\u8fd9\u4e2a\u4e34\u65f6\u8868\u4e2d\uff0c\u6700\u7ec8\u8fd4\u56de\u7ed9\u5ba2\u6237\u7aef<\/p>\n<p>ps:\u5b9e\u9645\u4e0a\u8fd9\u4e2a\u8fc7\u7a0b\u4e5f\u5e76\u4e0d\u662f\u7edd\u5bf9\u8fd9\u6837\u7684\uff0c\u4e2d\u95f4mysql\u4f1a\u6709\u90e8\u5206\u7684\u4f18\u5316\u4ee5\u8fbe\u5230\u6700\u4f73\u7684\u4f18\u5316\u6548\u679c\uff0c\u6bd4\u5982\u5728select\u7b5b\u9009\u51fa\u627e\u5230\u7684\u6570\u636e\u96c6\u3002<\/p>\n<h2>\u56db\u3001\u6267\u884c\u7684\u8ba1\u5212<\/h2>\n<h3>4.1:\u4ec0\u4e48\u662f\u6267\u884c\u8ba1\u5212<\/h3>\n<p>\u6267\u884c\u8ba1\u5212\u5c31\u662fsql\u7684\u6267\u884c\u67e5\u8be2\u7684\u987a\u5e8f\uff0c\u4ee5\u53ca\u5982\u4f55\u4f7f\u7528\u7d22\u5f15\u67e5\u8be2\uff0c\u8fd4\u56de\u7684\u7ed3\u679c\u96c6\u7684\u884c\u6570<\/p>\n<h3>4.2:\u6267\u884c\u8ba1\u5212\u7684\u5185\u5bb9<\/h3>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/\u6267\u884c\u8ba1\u5212.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/\u6267\u884c\u8ba1\u5212.png\" alt=\"\" \/><\/a><\/p>\n<h4>id<\/h4>\n<p>\u5305\u542b\u4e00\u7ec4\u6570\u5b57\uff0c\u8868\u793a\u67e5\u8be2\u4e2d\u6267\u884cselect\u5b50\u53e5\u6216\u64cd\u4f5c\u8868\u7684\u987a\u5e8f\u3002id\u4e00\u6837\uff0c\u6309\u7167\u987a\u5e8f\u6267\u884c\uff1bid\u8d8a\u5927\uff0c\u6267\u884c\u7684\u4f18\u5148\u7ea7\u5c31\u8d8a\u9ad8\uff08\u5982\u5b50\u67e5\u8be2\uff09<br \/>\n<a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212id_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212id_1.png\" alt=\"\" \/><\/a><br \/>\nid\u76f8\u540c\uff0c\u6267\u884c\u987a\u5e8f\u7531\u4e0a\u81f3\u4e0b<\/p>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212id_2.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212id_2.png\" alt=\"\" \/><\/a><br \/>\n\u5982\u679c\u662f\u5b50\u67e5\u8be2\uff0cid\u7684\u5e8f\u53f7\u4f1a\u9012\u589e\uff0cid\u503c\u8d8a\u5927\u4f18\u5148\u7ea7\u8d8a\u9ad8\uff0c\u8d8a\u5148\u88ab\u6267\u884c<\/p>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212id_3.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212id_3.png\" alt=\"\" \/><\/a><br \/>\nid\u5982\u679c\u76f8\u540c\uff0c\u53ef\u4ee5\u8ba4\u4e3a\u662f\u4e00\u7ec4\uff0c\u4ece\u4e0a\u5f80\u4e0b\u987a\u5e8f\u6267\u884c\uff1b\u5728\u6240\u6709\u7ec4\u4e2d\uff0cid\u503c\u8d8a\u5927\uff0c\u4f18\u5148\u7ea7\u8d8a\u9ad8\uff0c\u8d8a\u5148\u6267\u884c<\/p>\n<h3>select_type<\/h3>\n<p>\u8868\u793a\u67e5\u8be2\u4e2d\u6bcf\u4e2aselect\u5b50\u53e5\u7684\u7c7b\u578b\uff08\u7b80\u5355 OR\u590d\u6742\uff09<br \/>\n<a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212selecttype_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212selecttype_1.png\" alt=\"\" \/><\/a><br \/>\na.SIMPLE\uff1a\u67e5\u8be2\u4e2d\u4e0d\u5305\u542b\u5b50\u67e5\u8be2\u6216\u8005UNION<br \/>\nb.\u67e5\u8be2\u4e2d\u82e5\u5305\u542b\u4efb\u4f55\u590d\u6742\u7684\u5b50\u90e8\u5206\uff0c\u6700\u5916\u5c42\u67e5\u8be2\u5219\u88ab\u6807\u8bb0\u4e3a\uff1aPRIMARY<br \/>\nc.\u5728SELECT\u6216WHERE\u5217\u8868\u4e2d\u5305\u542b\u4e86\u5b50\u67e5\u8be2\uff0c\u8be5\u5b50\u67e5\u8be2\u88ab\u6807\u8bb0\u4e3a\uff1aSUBQUERY<br \/>\nd.\u5728FROM\u5217\u8868\u4e2d\u5305\u542b\u7684\u5b50\u67e5\u8be2\u88ab\u6807\u8bb0\u4e3a\uff1aDERIVED\uff08\u884d\u751f\uff09<br \/>\ne.\u82e5\u7b2c\u4e8c\u4e2aSELECT\u51fa\u73b0\u5728UNION\u4e4b\u540e\uff0c\u5219\u88ab\u6807\u8bb0\u4e3aUNION\uff1b\u82e5UNION\u5305\u542b\u5728  FROM\u5b50\u53e5\u7684\u5b50\u67e5\u8be2\u4e2d\uff0c\u5916\u5c42SELECT\u5c06\u88ab\u6807\u8bb0\u4e3a\uff1aDERIVED<br \/>\nf.\u4eceUNION\u8868\u83b7\u53d6\u7ed3\u679c\u7684SELECT\u88ab\u6807\u8bb0\u4e3a\uff1aUNION RESULT<\/p>\n<h3>type<\/h3>\n<p>MySQL\u5728\u8868\u4e2d\u627e\u5230\u6240\u9700\u884c\u7684\u65b9\u5f0f\uff0c\u53c8\u79f0\u201c\u8bbf\u95ee\u7c7b\u578b\u201d\uff0c\u5e38\u89c1\u7c7b\u578b\u5982\u4e0b\uff1a<br \/>\n<a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_1.png\" alt=\"\" \/><\/a><br \/>\n\u7531\u5de6\u81f3\u53f3\uff0c\u7531\u6700\u5dee\u5230\u6700\u597d<\/p>\n<ul>\n<li>a.ALL\uff1a<br \/>\nFull Table Scan\uff0c MySQL\u5c06\u904d\u5386\u5168\u8868\u4ee5\u627e\u5230\u5339\u914d\u7684\u884c<\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_2.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_2.png\" alt=\"\" \/><\/a><\/p>\n<ul>\n<li>b.index\uff1a<br \/>\nFull Index Scan\uff0cindex\u4e0eALL\u533a\u522b\u4e3aindex\u7c7b\u578b\u53ea\u904d\u5386\u7d22\u5f15\u6811<\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_3.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_3.png\" alt=\"\" \/><\/a><\/p>\n<ul>\n<li>c.range\uff1a<br \/>\n\u7d22\u5f15\u8303\u56f4\u626b\u63cf\uff0c\u5bf9\u7d22\u5f15\u7684\u626b\u63cf\u5f00\u59cb\u4e8e\u67d0\u4e00\u70b9\uff0c\u8fd4\u56de\u5339\u914d\u503c\u57df\u7684\u884c\uff0c\u5e38\u89c1\u4e8ebetween\u3001&lt;\u3001>\u7b49\u7684\u67e5\u8be2\uff0c\u4f46\u662f\u8981\u63a7\u5236\u67e5\u8be2\u7684\u65f6\u95f4\u8303\u56f4\uff0c\u4e00\u822c\u67e5\u8be2\u6570\u636e\u4e0d\u8981\u8d85\u8fc7\u6570\u636e\u603b\u6570\u7684 15%<\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_4.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_4.png\" alt=\"\" \/><\/a><\/p>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_5.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_5.png\" alt=\"\" \/><\/a><\/p>\n<p>range\u8bbf\u95ee\u7c7b\u578b\u7684\u4e0d\u540c\u5f62\u5f0f\u7684\u7d22\u5f15\u8bbf\u95ee\u6027\u80fd\u5dee\u5f02<\/p>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_6.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212type_6.png\" alt=\"\" \/><\/a><\/p>\n<ul>\n<li>d.ref\uff1a<br \/>\n\u975e\u552f\u4e00\u6027\u7d22\u5f15\u626b\u63cf\uff0c\u8fd4\u56de\u5339\u914d\u67d0\u4e2a\u5355\u72ec\u503c\u7684\u6240\u6709\u884c\u3002\u5e38\u89c1\u4e8e\u4f7f\u7528\u975e\u552f\u4e00\u7d22\u5f15\u5373\u552f\u4e00\u7d22\u5f15\u7684\u975e\u552f\u4e00\u524d\u7f00\u8fdb\u884c\u7684\u67e5\u627e\u3002<\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212ref_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212ref_1.png\" alt=\"\" \/><\/a> <a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212ref_2.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212ref_2.png\" alt=\"\" \/><\/a> <a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212ref_3.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212ref_3.png\" alt=\"\" \/><\/a><\/p>\n<ul>\n<li>e.eq_ref\uff1a<br \/>\n\u552f\u4e00\u6027\u7d22\u5f15\u626b\u63cf\uff0c\u5bf9\u4e8e\u6bcf\u4e2a\u7d22\u5f15\u952e\uff0c\u8868\u4e2d\u53ea\u6709\u4e00\u6761\u8bb0\u5f55\u4e0e\u4e4b\u5339\u914d\u3002\u5e38\u89c1\u4e8e\u4e3b\u952e\u6216\u552f\u4e00\u7d22\u5f15\u626b\u63cf<\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212eqref_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212eqref_1.png\" alt=\"\" \/><\/a><\/p>\n<ul>\n<li>f.const\u3001system\uff1a<br \/>\n\u5f53MySQL\u5bf9\u67e5\u8be2\u67d0\u90e8\u5206\u8fdb\u884c\u4f18\u5316\uff0c\u5e76\u8f6c\u6362\u4e3a\u4e00\u4e2a\u5e38\u91cf\u65f6\uff0c\u4f7f\u7528\u8fd9\u4e9b\u7c7b\u578b\u8bbf\u95ee\u3002\u5982\u5c06\u4e3b\u952e\u7f6e\u4e8ewhere\u5217\u8868\u4e2d\uff0cMySQL\u5c31\u80fd\u5c06\u8be5\u67e5\u8be2\u8f6c\u6362\u4e3a\u4e00\u4e2a\u5e38\u91cf<\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212const_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212const_1.png\" alt=\"\" \/><\/a><br \/>\nsystem\u662fconst\u7c7b\u578b\u7684\u7279\u4f8b\uff0c\u5f53\u67e5\u8be2\u7684\u8868\u53ea\u6709\u4e00\u884c\u7684\u60c5\u51b5\u4e0b\uff0c \u4f7f\u7528system<\/p>\n<ul>\n<li>g.NULL\uff1a<br \/>\nMySQL\u5728\u4f18\u5316\u8fc7\u7a0b\u4e2d\u5206\u89e3\u8bed\u53e5\uff0c\u6267\u884c\u65f6\u751a\u81f3\u4e0d\u7528\u8bbf\u95ee\u8868\u6216\u7d22\u5f15<\/li>\n<\/ul>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212null_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212null_1.png\" alt=\"\" \/><\/a><\/p>\n<h3>possible_keys<\/h3>\n<p>\u6307\u51faMySQL\u80fd\u4f7f\u7528\u54ea\u4e2a\u7d22\u5f15\u5728\u8868\u4e2d\u627e\u5230\u884c\uff0c\u67e5\u8be2\u6d89\u53ca\u5230\u7684\u5b57\u6bb5\u4e0a\u82e5\u5b58\u5728\u7d22\u5f15\uff0c\u5219\u8be5\u7d22\u5f15\u5c06\u88ab\u5217\u51fa\uff0c\u4f46\u4e0d\u4e00\u5b9a\u88ab\u67e5\u8be2\u4f7f\u7528<\/p>\n<h3>key<\/h3>\n<p>\u663e\u793aMySQL\u5728\u67e5\u8be2\u4e2d\u5b9e\u9645\u4f7f\u7528\u7684\u7d22\u5f15\uff0c\u82e5\u6ca1\u6709\u4f7f\u7528\u7d22\u5f15\uff0c\u663e\u793a\u4e3aNULL\u3002<br \/>\nTIPS\uff1a\u67e5\u8be2\u4e2d\u82e5\u4f7f\u7528\u4e86\u8986\u76d6\u7d22\u5f15\uff0c\u5219\u8be5\u7d22\u5f15\u4ec5\u51fa\u73b0\u5728key\u5217\u8868\u4e2d\u3002<br \/>\n\u8986\u76d6\u7d22\u5f15\uff1a\u67e5\u8be2\u6570\u636e\u53ea\u9700\u8981\u901a\u8fc7\u7d22\u5f15\u5c31\u53ef\u4ee5\u67e5\u8be2\u51fa\uff0c\u598255\u4e07\u6761\u6570\u636e\uff0c\u4f7f\u7528\u7d22\u5f15\uff0c\u7acb\u523b\u53ef\u4ee5\u67e5\u8be2\u51fa 2000\u6761\u6570\u636e\uff0c\u540c\u65f6Extra\u5b57\u6bb5\u662fUsing index<br \/>\n<a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212key_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212key_1.png\" alt=\"\" \/><\/a><\/p>\n<h3>key_len<\/h3>\n<p>\u8868\u793a\u7d22\u5f15\u4e2d\u4f7f\u7528\u7684\u5b57\u8282\u6570\uff0c\u53ef\u901a\u8fc7\u8be5\u5217\u8ba1\u7b97\u67e5\u8be2\u4e2d\u4f7f\u7528\u7684\u7d22\u5f15\u7684\u957f\u5ea6<\/p>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212keylen_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212keylen_1.png\" alt=\"\" \/><\/a> <a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212keylen_2.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212keylen_2.png\" alt=\"\" \/><\/a><br \/>\nkey_len\u663e\u793a\u7684\u503c\u4e3a\u7d22\u5f15\u5b57\u6bb5\u7684\u6700\u5927\u53ef\u80fd\u957f\u5ea6\uff0c\u5e76\u975e\u5b9e\u9645\u4f7f\u7528\u957f\u5ea6\uff0c\u5373key_len\u662f\u6839\u636e\u8868\u5b9a\u4e49\u8ba1\u7b97\u800c\u5f97\uff0c\u4e0d\u662f\u901a\u8fc7\u8868\u5185\u68c0\u7d22\u51fa\u7684<\/p>\n<h3>ref<\/h3>\n<p>\u8868\u793a\u4e0a\u8ff0\u8868\u7684\u8fde\u63a5\u5339\u914d\u6761\u4ef6\uff0c\u5373\u54ea\u4e9b\u5217\u6216\u5e38\u91cf\u88ab\u7528\u4e8e\u67e5\u627e\u7d22\u5f15\u5217\u4e0a\u7684\u503c<\/p>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212kref_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212kref_1.png\" alt=\"\" \/><\/a><\/p>\n<h3>rows<\/h3>\n<p>\u8868\u793aMySQL\u6839\u636e\u8868\u7edf\u8ba1\u4fe1\u606f\u53ca\u7d22\u5f15\u9009\u7528\u60c5\u51b5\uff0c\u4f30\u7b97\u7684\u627e\u5230\u6240\u9700\u7684\u8bb0\u5f55\u6240\u9700\u8981\u8bfb\u53d6\u7684\u884c\u6570<\/p>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212row_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212row_1.png\" alt=\"\" \/><\/a><\/p>\n<h3>Extra<\/h3>\n<p>\u5305\u542b\u4e0d\u9002\u5408\u5728\u5176\u4ed6\u5217\u4e2d\u663e\u793a\u4f46\u5341\u5206\u91cd\u8981\u7684\u989d\u5916\u4fe1\u606f<\/p>\n<ul>\n<li>a.Using index<\/li>\n<\/ul>\n<p>\u8be5\u503c\u8868\u793a\u76f8\u5e94\u7684select\u64cd\u4f5c\u4e2d\u4f7f\u7528\u4e86\u8986\u76d6\u7d22\u5f15\uff08Covering Index\uff09<\/p>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212extra_1.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212extra_1.png\" alt=\"\" \/><\/a><br \/>\nTIPS\uff1a\u8986\u76d6\u7d22\u5f15\uff08Covering Index\uff09<\/p>\n<p>MySQL\u53ef\u4ee5\u5229\u7528\u7d22\u5f15\u8fd4\u56deselect\u5217\u8868\u4e2d\u7684\u5b57\u6bb5\uff0c\u800c\u4e0d\u5fc5\u6839\u636e\u7d22\u5f15\u518d\u6b21\u8bfb\u53d6\u6570\u636e\u6587\u4ef6<\/p>\n<p>\u5305\u542b\u6240\u6709\u6ee1\u8db3\u67e5\u8be2\u9700\u8981\u7684\u6570\u636e\u7684\u7d22\u5f15\u79f0\u4e3a \u8986\u76d6\u7d22\u5f15\uff08Covering Index\uff09<\/p>\n<p>\u6ce8\u610f\uff1a<br \/>\n\u5982\u679c\u8981\u4f7f\u7528\u8986\u76d6\u7d22\u5f15\uff0c\u4e00\u5b9a\u8981\u6ce8\u610fselect\u5217\u8868\u4e2d\u53ea\u53d6\u51fa\u9700\u8981\u7684\u5217\uff0c\u4e0d\u53efselect *\uff0c\u56e0\u4e3a\u5982\u679c\u5c06\u6240\u6709\u5b57\u6bb5\u4e00\u8d77\u505a\u7d22\u5f15\u4f1a\u5bfc\u81f4\u7d22\u5f15\u6587\u4ef6\u8fc7\u5927\uff0c\u67e5\u8be2\u6027\u80fd\u4e0b\u964d<\/p>\n<ul>\n<li>b.Using where<\/li>\n<\/ul>\n<p>\u8868\u793aMySQL\u670d\u52a1\u5668\u5728\u5b58\u50a8\u5f15\u64ce\u53d7\u5230\u8bb0\u5f55\u540e\u8fdb\u884c\u201c\u540e\u8fc7\u6ee4\u201d\uff08Post-filter\uff09,<br \/>\n\u5982\u679c\u67e5\u8be2\u672a\u80fd\u4f7f\u7528\u7d22\u5f15\uff0cUsing where\u7684\u4f5c\u7528\u53ea\u662f\u63d0\u9192\u6211\u4eecMySQL\u5c06\u7528where\u5b50\u53e5\u6765\u8fc7\u6ee4\u7ed3\u679c\u96c6<\/p>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212extra_2.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212extra_2.png\" alt=\"\" \/><\/a><\/p>\n<ul>\n<li>c.Using temporary<\/li>\n<\/ul>\n<p>\u8868\u793aMySQL\u9700\u8981\u4f7f\u7528\u4e34\u65f6\u8868\u6765\u5b58\u50a8\u7ed3\u679c\u96c6\uff0c\u5e38\u89c1\u4e8e\u6392\u5e8f\u548c\u5206\u7ec4\u67e5\u8be2<\/p>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212extra_3.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212extra_3.png\" alt=\"\" \/><\/a><\/p>\n<ul>\n<li>d.Using filesort<\/li>\n<\/ul>\n<p>MySQL\u4e2d\u65e0\u6cd5\u5229\u7528\u7d22\u5f15\u5b8c\u6210\u7684\u6392\u5e8f\u64cd\u4f5c\u79f0\u4e3a\u201c\u6587\u4ef6\u6392\u5e8f\u201d<br \/>\n\u5f88\u591a\u573a\u666f\u90fd\u662f\u7d22\u5f15\u662f\u4e00\u4e2a\u5b57\u6bb5\uff0corder by \u6392\u5e8f\u7684\u5b57\u6bb5\u4e0e\u7d22\u5f15\u5b57\u6bb5\u4e0d\u4e00\u81f4\uff0c\u5bfc\u81f4\u7684Using fileSort;<br \/>\n\u6b64\u65f6\u53ef\u4ee5\u7ed9\u6392\u5e8f\u5b57\u6bb5\u548cwhere\u6761\u4ef6\u5b57\u6bb5\uff0c\u6dfb\u52a0\u4e3a\u7ec4\u5408\u7d22\u5f15\uff0c\u540c\u65f6\u4fdd\u8bc1\u7d22\u5f15\u67e5\u8be2\u7684\u6570\u636e\u4e0d\u8d85\u8fc7\u603b\u91cf\u768415%\uff0c\u907f\u514dfileSort<\/p>\n<p><a href=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212extra_4.png\"><img src=\"http:\/\/www.cgh0610.cn\/wp-content\/uploads\/2021\/08\/mysql\u6267\u884c\u8ba1\u5212extra_4.png\" alt=\"\" \/><\/a><\/p>\n<p>\u6ce8\uff1a\u56de\u8868\u7684\u542b\u4e49\u662f\uff0c\u5148\u6839\u636e\u7d22\u5f15\u67e5\u8be2\u6570\u636e\uff0c\u7136\u540e\u5728\u6839\u636e\u786e\u5b9a\u7684\u6570\u636eid\u548c\u67e5\u8be2\u6761\u4ef6\u518d\u53bb\u67e5\u8be2\u5177\u4f53\u7684\u6570\u636e\u7684\u8fc7\u7a0b<\/p>\n<h2>\u4e94\u3001EXPLAIN\u7684\u5c40\u9650<\/h2>\n<p>\u2022EXPLAIN\u4e0d\u4f1a\u544a\u8bc9\u4f60\u5173\u4e8e\u89e6\u53d1\u5668\u3001\u5b58\u50a8\u8fc7\u7a0b\u7684\u4fe1\u606f\u6216\u7528\u6237\u81ea\u5b9a\u4e49\u51fd\u6570\u5bf9\u67e5\u8be2\u7684\u5f71\u54cd\u60c5\u51b5<br \/>\n\u2022EXPLAIN\u4e0d\u8003\u8651\u5404\u79cdCache<br \/>\n\u2022EXPLAIN\u4e0d\u80fd\u663e\u793aMySQL\u5728\u6267\u884c\u67e5\u8be2\u65f6\u6240\u4f5c\u7684\u4f18\u5316\u5de5\u4f5c<br \/>\n\u2022\u90e8\u5206\u7edf\u8ba1\u4fe1\u606f\u662f\u4f30\u7b97\u7684\uff0c\u5e76\u975e\u7cbe\u786e\u503c<br \/>\n\u2022EXPALIN\u53ea\u80fd\u89e3\u91caSELECT\u64cd\u4f5c\uff0c\u5176\u4ed6\u64cd\u4f5c\u8981\u91cd\u5199\u4e3aSELECT\u540e\u67e5\u770b\u6267\u884c\u8ba1\u5212<\/p>\n<h2>\u516d\u3001\u603b\u7ed3<\/h2>\n<p>\u672c\u6587\u4eceMySql\u6267\u884c\u8fc7\u7a0b\u3001\u6267\u884c\u8fc7\u7a0b\u7684\u72b6\u6001\uff0c\u5230MySql\u7684\u6267\u884c\u987a\u5e8f\u3001MySql\u7684\u6267\u884c\u8ba1\u5212\uff0c\u4e00\u8def\u505a\u4e86\u8be6\u7ec6\u7684\u603b\u7ed3\uff0c\u7406\u89e3\u8fd9\u4e9b\u6709\u52a9\u4e8e\u63d0\u9ad8\u6211\u4eec\u5bf9mysql\u7684\u603b\u4f53\u7406\u89e3\u548c\u628a\u63e1\uff0c\u6709\u52a9\u4e8e\u6211\u4eec\u5bf9sql\u8bed\u53e5\u8fdb\u884c\u4f18\u5316\uff0c\u4ee5\u53ca\u660e\u767dmysql\u4e2d\u7684sql\u8bed\u53e5\u4ece\u5199\u51fa\u6765\u5230\u6700\u7ec8\u6267\u884c\u7684\u8f68\u8ff9\u3002\u5e0c\u671b\u80fd\u5e2e\u5230\u5927\u5bb6\u3002<\/p>\n<p>\u53c2\u8003\u94fe\u63a5\uff1a<br \/>\n1.<a href=\"https:\/\/www.cnblogs.com\/wyq178\/p\/11576065.html\" title=\"mysql\u6267\u884c\u8fc7\u7a0b\u4ee5\u53ca\u987a\u5e8f\">mysql\u6267\u884c\u8fc7\u7a0b\u4ee5\u53ca\u987a\u5e8f<\/a><br \/>\n2.<a href=\"https:\/\/blog.csdn.net\/csndhu\/article\/details\/88176564\" title=\"MySql\u6267\u884c\u987a\u5e8f\u53ca\u6267\u884c\u8ba1\u5212\">MySql\u6267\u884c\u987a\u5e8f\u53ca\u6267\u884c\u8ba1\u5212<\/a><br \/>\n3.<a href=\"https:\/\/www.cnblogs.com\/ggjucheng\/archive\/2012\/11\/11\/2765237.html\" title=\"MySQL\u6267\u884c\u8ba1\u5212\u89e3\u8bfb\">MySQL\u6267\u884c\u8ba1\u5212\u89e3\u8bfb<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u524d\u8a00\uff1aMySql\u662f\u6211\u4eec\u5e73\u5e38\u7528\u7684\u6bd4\u8f83\u591a\u7684\u6570\u636e\u5e93\uff0c\u4f46\u662f\u65f6\u95f4\u4e45\u4e86\u540e\u603b\u4f1a\u6216\u591a\u6216\u5c11\u5fd8\u8bb0\u4e86\u4e00\u6761sql\u5b8c\u6574\u7684\u6267\u884c\u8fc7\u7a0b\uff0c\u4eca\u5929\u67e5 &hellip; <a href=\"https:\/\/www.cgh0610.cn\/?p=207\" class=\"more-link\">\u7ee7\u7eed\u9605\u8bfb<span class=\"screen-reader-text\">MySql\u6267\u884c\u8fc7\u7a0b\u3001\u6267\u884c\u987a\u5e8f\u3001\u6267\u884c\u8ba1\u5212<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"aside","meta":[],"categories":[39,12,1],"tags":[],"_links":{"self":[{"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/posts\/207"}],"collection":[{"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=207"}],"version-history":[{"count":7,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/posts\/207\/revisions"}],"predecessor-version":[{"id":245,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/posts\/207\/revisions\/245"}],"wp:attachment":[{"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=207"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=207"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=207"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}