{"id":305624,"date":"2022-12-15T15:24:47","date_gmt":"2022-12-15T07:24:47","guid":{"rendered":"https:\/\/www.idc.net\/help\/305624\/"},"modified":"2022-12-15T15:24:47","modified_gmt":"2022-12-15T07:24:47","slug":"%e5%85%b3%e4%ba%8emysql%e6%95%b0%e6%8d%ae%e5%ba%93%e6%80%a7%e8%83%bd%e4%bc%98%e5%8c%96%e6%96%b9%e6%b3%95%ef%bc%8c%e7%9c%8b%e8%bf%99%e4%b8%80%e7%af%87%e6%96%87%e7%ab%a0%e5%b0%b1%e5%a4%9f%e4%ba%86","status":"publish","type":"post","link":"https:\/\/idc.net\/help\/305624\/","title":{"rendered":"\u5173\u4e8eMySQL\u6570\u636e\u5e93\u6027\u80fd\u4f18\u5316\u65b9\u6cd5\uff0c\u770b\u8fd9\u4e00\u7bc7\u6587\u7ae0\u5c31\u591f\u4e86"},"content":{"rendered":"<p style=\"text-align: center\">\n<p>\u6570\u636e\u5e93\u5927\u91cf\u5e94\u7528\u7a0b\u5e8f\u5f00\u53d1\u9879\u76ee\u4e2d\uff0c\u5927\u591a\u6570\u60c5\u51b5\u4e0b\uff0c\u6570\u636e\u5e93\u7684\u64cd\u4f5c\u6027\u80fd\u6210\u4e3a\u6574\u4e2a\u5e94\u7528\u7684\u6027\u80fd\u74f6\u9888\u3002\u6570\u636e\u5e93\u7684\u6027\u80fd\u662f\u7a0b\u5e8f\u5458\u9700\u8981\u53bb\u5173\u6ce8\u7684\u4e8b\u60c5\uff0c\u5f53\u8bbe\u8ba1\u6570\u636e\u5e93\u8868\u7ed3\u6784\u4ee5\u53ca\u64cd\u4f5c\u6570\u636e\u5e93(\u5c24\u5176\u662f\u67e5\u8be2\u6570\u636e\u65f6)\uff0c\u90fd\u9700\u8981\u6ce8\u610f\u6570\u636e\u64cd\u4f5c\u7684\u6027\u80fd\u3002\u672c\u6587\u6211\u4eec\u4ee5MySQL\u6570\u636e\u5e93\u4e3a\u4f8b\u8fdb\u884c\u8ba8\u8bba\u3002<\/p>\n<h3>\u4e00\u3001\u6570\u636e\u5e93\u4f18\u5316\u76ee\u6807<\/h3>\n<h4>1. \u51cf\u5c11 IO \u6b21\u6570<\/h4>\n<p>IO\u6c38\u8fdc\u662f\u6570\u636e\u5e93\u6700\u5bb9\u6613\u74f6\u9888\u7684\u5730\u65b9\uff0c\u8fd9\u662f\u7531\u6570\u636e\u5e93\u7684\u804c\u8d23\u6240\u51b3\u5b9a\u7684\uff0c\u5927\u90e8\u5206\u6570\u636e\u5e93\u64cd\u4f5c\u4e2d\u8d85\u8fc790%\u7684\u65f6\u95f4\u90fd\u662f IO \u64cd\u4f5c\u6240\u5360\u7528\u7684\uff0c\u51cf\u5c11 IO \u6b21\u6570\u662f SQL \u4f18\u5316\u4e2d\u9700\u8981\u7b2c\u4e00\u4f18\u5148\u8003\u8651\uff0c\u5f53\u7136\uff0c\u4e5f\u662f\u6536\u6548\u6700\u660e\u663e\u7684\u4f18\u5316\u624b\u6bb5\u3002<\/p>\n<h4>2. \u964d\u4f4e CPU \u8ba1\u7b97<\/h4>\n<p>\u9664\u4e86 IO \u74f6\u9888\u4e4b\u5916\uff0cSQL\u4f18\u5316\u4e2d\u9700\u8981\u8003\u8651\u7684\u5c31\u662f CPU \u8fd0\u7b97\u91cf\u7684\u4f18\u5316\u4e86\u3002order by,group by,distinct \u2026 \u90fd\u662f\u6d88\u8017 CPU \u7684\u5927\u6237(\u8fd9\u4e9b\u64cd\u4f5c\u57fa\u672c\u4e0a\u90fd\u662f CPU \u5904\u7406\u5185\u5b58\u4e2d\u7684\u6570\u636e\u6bd4\u8f83\u8fd0\u7b97)\u3002\u5f53\u6211\u4eec\u7684 IO \u4f18\u5316\u505a\u5230\u4e00\u5b9a\u9636\u6bb5\u4e4b\u540e\uff0c\u964d\u4f4e CPU\u8ba1\u7b97\u4e5f\u5c31\u6210\u4e3a\u4e86\u6211\u4eec SQL \u4f18\u5316\u7684\u91cd\u8981\u76ee\u6807\u3002<\/p>\n<p style=\"text-align: center\">\n<p style=\"text-align: center\">MySql\u67e5\u8be2\u8fc7\u7a0b<\/p>\n<h3>\u4e8c\u3001\u6570\u636e\u5e93\u4f18\u5316\u65b9\u6cd5<\/h3>\n<h4>1. SQL\u8bed\u53e5\u4f18\u5316<\/h4>\n<p>\u660e\u786e\u4e86\u4f18\u5316\u76ee\u6807\u4e4b\u540e\uff0c\u6211\u4eec\u9700\u8981\u786e\u5b9a\u8fbe\u5230\u6211\u4eec\u76ee\u6807\u7684\u65b9\u6cd5\u3002\u5bf9\u4e8eSQL\u8bed\u53e5\u6765\u8bf4\uff0c\u8fbe\u5230\u4e0a\u8ff02\u4e2a\u4f18\u5316\u76ee\u6807\u7684\u65b9\u6cd5\u5176\u5b9e\u53ea\u6709\u4e00\u4e2a\uff0c\u90a3\u5c31\u662f\u6539\u53d8SQL\u7684\u6267\u884c\u8ba1\u5212\uff0c\u8ba9\u4ed6\u5c3d\u91cf\u201c\u5c11\u8d70\u5f2f\u8def\u201d\uff0c\u5c3d\u91cf\u901a\u8fc7\u5404\u79cd\u201c\u6377\u5f84\u201d\u6765\u627e\u5230\u6211\u4eec\u9700\u8981\u7684\u6570\u636e\uff0c\u4ee5\u8fbe\u5230\u201c\u51cf\u5c11IO\u6b21\u6570\u201d\u548c\u201c\u964d\u4f4eCPU\u8ba1\u7b97\u201d\u7684\u76ee\u6807\u3002<\/p>\n<p>(1) \u5c3d\u91cf\u5c11 join\u3002MySQL \u7684\u4f18\u52bf\u5728\u4e8e\u7b80\u5355\uff0c\u4f46\u8fd9\u5728\u67d0\u4e9b\u65b9\u9762\u5176\u5b9e\u4e5f\u662f\u5176\u52a3\u52bf\u3002MySQL\u4f18\u5316\u5668\u6548\u7387\u9ad8\uff0c\u4f46\u662f\u7531\u4e8e\u5176\u7edf\u8ba1\u4fe1\u606f\u7684\u91cf\u6709\u9650\uff0c\u4f18\u5316\u5668\u5de5\u4f5c\u8fc7\u7a0b\u51fa\u73b0\u504f\u5dee\u7684\u53ef\u80fd\u6027\u4e5f\u5c31\u66f4\u591a\u3002\u5bf9\u4e8e\u590d\u6742\u7684\u591a\u8868 Join\uff0c\u4e00\u65b9\u9762\u7531\u4e8e\u5176\u4f18\u5316\u5668\u53d7\u9650\uff0c\u518d\u8005\u5728Join\u8fd9\u65b9\u9762\u6240\u4e0b\u7684\u529f\u592b\u8fd8\u4e0d\u591f\uff0c\u6240\u4ee5\u6027\u80fd\u8868\u73b0\u79bbOracle\u7b49\u5173\u7cfb\u578b\u6570\u636e\u5e93\u524d\u8f88\u8fd8\u662f\u6709\u4e00\u5b9a\u8ddd\u79bb\u3002\u4f46\u5982\u679c\u662f\u7b80\u5355\u7684\u5355\u8868\u67e5\u8be2\uff0c\u8fd9\u4e00\u5dee\u8ddd\u5c31\u4f1a\u6781\u5c0f\u751a\u81f3\u5728\u6709\u4e9b\u573a\u666f\u4e0b\u8981\u4f18\u4e8e\u8fd9\u4e9b\u6570\u636e\u5e93\u524d\u8f88\u3002<\/p>\n<p>(2) \u5c3d\u91cf\u5c11\u6392\u5e8f<\/p>\n<p>(3) \u6392\u5e8f\u64cd\u4f5c\u4f1a\u6d88\u8017\u8f83\u591a\u7684 CPU \u8d44\u6e90\uff0c\u6240\u4ee5\u51cf\u5c11\u6392\u5e8f\u53ef\u4ee5\u5728\u7f13\u5b58\u547d\u4e2d\u7387\u9ad8\u7b49 IO \u80fd\u529b\u8db3\u591f\u7684\u573a\u666f\u4e0b\u4f1a\u8f83\u5927\u5f71\u54cd SQL\u7684\u54cd\u5e94\u65f6\u95f4\u3002<\/p>\n<p>(4) \u5c3d\u91cf\u907f\u514d select *\uff0c\u5e76\u5c3d\u91cf\u7528join\u4ee3\u66ff\u5b50\u67e5\u8be2<\/p>\n<p>(5) \u5c3d\u91cf\u5c11\u4f7f\u7528\u201cor\u201d\u5173\u952e\u5b57<\/p>\n<p>\u5f53 where \u5b50\u53e5\u4e2d\u5b58\u5728\u591a\u4e2a\u6761\u4ef6\u4ee5\u201c\u6216\u201d\u5e76\u5b58\u7684\u65f6\u5019\uff0cMySQL \u7684\u4f18\u5316\u5668\u5e76\u6ca1\u6709\u5f88\u597d\u7684\u89e3\u51b3\u5176\u6267\u884c\u8ba1\u5212\u4f18\u5316\u95ee\u9898\uff0c\u518d\u52a0\u4e0a MySQL \u7279\u6709\u7684 SQL \u4e0e Storage \u5206\u5c42\u67b6\u6784\u65b9\u5f0f\uff0c\u9020\u6210\u4e86\u5176\u6027\u80fd\u6bd4\u8f83\u4f4e\u4e0b\uff0c\u5f88\u591a\u65f6\u5019\u4f7f\u7528 union all \u6216\u8005\u662funion(\u5fc5\u8981\u7684\u65f6\u5019)\u7684\u65b9\u5f0f\u6765\u4ee3\u66ff\u201cor\u201d\u4f1a\u5f97\u5230\u66f4\u597d\u7684\u6548\u679c\u3002<\/p>\n<p>(6) \u5c3d\u91cf\u7528 union all \u4ee3\u66ff union<\/p>\n<p>union \u548c union all \u7684\u5dee\u5f02\u4e3b\u8981\u662f\u524d\u8005\u9700\u8981\u5c06\u4e24\u4e2a(\u6216\u8005\u591a\u4e2a)\u7ed3\u679c\u96c6\u5408\u5e76\u540e\u518d\u8fdb\u884c\u552f\u4e00\u6027\u8fc7\u6ee4\u64cd\u4f5c\uff0c\u8fd9\u5c31\u4f1a\u6d89\u53ca\u5230\u6392\u5e8f\uff0c\u589e\u52a0\u5927\u91cf\u7684 CPU \u8fd0\u7b97\uff0c\u52a0\u5927\u8d44\u6e90\u6d88\u8017\u53ca\u5ef6\u8fdf\u3002\u6240\u4ee5\u5f53\u6211\u4eec\u53ef\u4ee5\u786e\u8ba4\u4e0d\u53ef\u80fd\u51fa\u73b0\u91cd\u590d\u7ed3\u679c\u96c6\u6216\u8005\u4e0d\u5728\u4e4e\u91cd\u590d\u7ed3\u679c\u96c6\u7684\u65f6\u5019\uff0c\u5c3d\u91cf\u4f7f\u7528 union all \u800c\u4e0d\u662f union\u3002<\/p>\n<p>(7) \u907f\u514d\u7c7b\u578b\u8f6c\u6362<\/p>\n<p>(8) \u80fd\u7528DISTINCT\u7684\u5c31\u4e0d\u7528GROUP BY<\/p>\n<p>(9) \u5c3d\u91cf\u4e0d\u8981\u7528SELECT INTO\u8bed\u53e5 ?<\/p>\n<p>(10) \u4ece\u5168\u5c40\u51fa\u53d1\u4f18\u5316\uff0c\u800c\u4e0d\u662f\u7247\u9762\u8c03\u6574<\/p>\n<p>SQL \u4f18\u5316\u4e0d\u80fd\u662f\u5355\u72ec\u9488\u5bf9\u67d0\u4e00\u4e2a\u8fdb\u884c\uff0c\u800c\u5e94\u5145\u5206\u8003\u8651\u7cfb\u7edf\u4e2d\u6240\u6709\u7684 SQL\uff0c\u5c24\u5176\u662f\u5728\u901a\u8fc7\u8c03\u6574\u7d22\u5f15\u4f18\u5316 SQL\u7684\u6267\u884c\u8ba1\u5212\u7684\u65f6\u5019\uff0c\u5343\u4e07\u4e0d\u80fd\u987e\u6b64\u5931\u5f7c\uff0c\u56e0\u5c0f\u5931\u5927\u3002<\/p>\n<h4>2. \u8868\u7ed3\u6784\u4f18\u5316<\/h4>\n<p>MySQL\u6570\u636e\u5e93\u662f\u57fa\u4e8e\u884c(Row)\u5b58\u50a8\u7684\u6570\u636e\u5e93\uff0c\u800c\u6570\u636e\u5e93\u64cd\u4f5c IO \u7684\u65f6\u5019\u662f\u4ee5 page(block)\u7684\u65b9\u5f0f\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u5982\u679c\u6211\u4eec\u6bcf\u6761\u8bb0\u5f55\u6240\u5360\u7528\u7684\u7a7a\u95f4\u91cf\u51cf\u5c0f\uff0c\u5c31\u4f1a\u4f7f\u6bcf\u4e2apage\u4e2d\u53ef\u5b58\u653e\u7684\u6570\u636e\u884c\u6570\u589e\u5927\uff0c\u90a3\u4e48\u6bcf\u6b21 IO \u53ef\u8bbf\u95ee\u7684\u884c\u6570\u4e5f\u5c31\u589e\u591a\u4e86\u3002\u53cd\u8fc7\u6765\u8bf4\uff0c\u5904\u7406\u76f8\u540c\u884c\u6570\u7684\u6570\u636e\uff0c\u9700\u8981\u8bbf\u95ee\u7684 page \u5c31\u4f1a\u51cf\u5c11\uff0c\u4e5f\u5c31\u662f IO \u64cd\u4f5c\u6b21\u6570\u964d\u4f4e\uff0c\u76f4\u63a5\u63d0\u5347\u6027\u80fd\u3002<\/p>\n<p>(1) \u6570\u636e\u7c7b\u578b\u9009\u62e9<\/p>\n<p>\u539f\u5219\u662f\uff1a\u6570\u636e\u884c\u7684\u957f\u5ea6\u4e0d\u8981\u8d85\u8fc78020\u5b57\u8282\uff0c\u5982\u679c\u8d85\u8fc7\u8fd9\u4e2a\u957f\u5ea6\u7684\u8bdd\u5728\u7269\u7406\u9875\u4e2d\u8fd9\u6761\u6570\u636e\u4f1a\u5360\u7528\u4e24\u884c\u4ece\u800c\u9020\u6210\u5b58\u50a8\u788e\u7247\uff0c\u964d\u4f4e\u67e5\u8be2\u6548\u7387;\u5b57\u6bb5\u7684\u957f\u5ea6\u5728\u6700\u5927\u9650\u5ea6\u7684\u6ee1\u8db3\u53ef\u80fd\u7684\u9700\u8981\u7684\u524d\u63d0\u4e0b\uff0c\u5e94\u8be5\u5c3d\u53ef\u80fd\u7684\u8bbe\u5f97\u77ed\u4e00\u4e9b\uff0c\u8fd9\u6837\u53ef\u4ee5\u63d0\u9ad8\u67e5\u8be2\u7684\u6548\u7387\uff0c\u800c\u4e14\u5728\u5efa\u7acb\u7d22\u5f15\u7684\u65f6\u5019\u4e5f\u53ef\u4ee5\u51cf\u5c11\u8d44\u6e90\u7684\u6d88\u8017\u3002<\/p>\n<ul>\n<li>\u6570\u5b57\u7c7b\u578b\uff1a\u975e\u4e07\u4e0d\u5f97\u5df2\u4e0d\u8981\u4f7f\u7528DOUBLE\uff0c\u4e0d\u4ec5\u4ec5\u53ea\u662f\u5b58\u50a8\u957f\u5ea6\u7684\u95ee\u9898\uff0c\u540c\u65f6\u8fd8\u4f1a\u5b58\u5728\u7cbe\u786e\u6027\u7684\u95ee\u9898\u3002\u540c\u6837\uff0c\u56fa\u5b9a\u7cbe\u5ea6\u7684\u5c0f\u6570\uff0c\u4e5f\u4e0d\u5efa\u8bae\u4f7f\u7528DECIMAL\uff0c\u5efa\u8bae\u4e58\u4ee5\u56fa\u5b9a\u500d\u6570\u8f6c\u6362\u6210\u6574\u6570\u5b58\u50a8\uff0c\u53ef\u4ee5\u5927\u5927\u8282\u7701\u5b58\u50a8\u7a7a\u95f4\uff0c\u4e14\u4e0d\u4f1a\u5e26\u6765\u4efb\u4f55\u9644\u52a0\u7ef4\u62a4\u6210\u672c\u3002<\/li>\n<li>\u5b57\u7b26\u7c7b\u578b\uff1a\u5b9a\u957f\u5b57\u6bb5\uff0c\u5efa\u8bae\u4f7f\u7528 CHAR \u7c7b\u578b(char\u67e5\u8be2\u5feb\uff0c\u4f46\u662f\u8017\u5b58\u50a8\u7a7a\u95f4\uff0c\u53ef\u7528\u4e8e\u7528\u6237\u540d\u3001\u5bc6\u7801\u7b49\u957f\u5ea6\u53d8\u5316\u4e0d\u5927\u7684\u5b57\u6bb5)\uff0c\u4e0d\u5b9a\u957f\u5b57\u6bb5\u5c3d\u91cf\u4f7f\u7528VARCHAR(varchar\u67e5\u8be2\u76f8\u5bf9\u6162\u4e00\u4e9b\u4f46\u662f\u8282\u7701\u5b58\u50a8\u7a7a\u95f4\uff0c\u53ef\u7528\u4e8e\u8bc4\u8bba\u7b49\u957f\u5ea6\u53d8\u5316\u5927\u7684\u5b57\u6bb5)\uff0c\u4e14\u4ec5\u4ec5\u8bbe\u5b9a\u9002\u5f53\u7684\u6700\u5927\u957f\u5ea6\uff0c\u800c\u4e0d\u662f\u975e\u5e38\u968f\u610f\u7684\u7ed9\u4e00\u4e2a\u5f88\u5927\u7684\u6700\u5927\u957f\u5ea6\u9650\u5b9a\uff0c\u56e0\u4e3a\u4e0d\u540c\u7684\u957f\u5ea6\u8303\u56f4\uff0cMySQL\u4e5f\u4f1a\u6709\u4e0d\u4e00\u6837\u7684\u5b58\u50a8\u5904\u7406\u3002<\/li>\n<li>\u65f6\u95f4\u7c7b\u578b\uff1a\u5c3d\u91cf\u4f7f\u7528TIMESTAMP\u7c7b\u578b\uff0c\u56e0\u4e3a\u5176\u5b58\u50a8\u7a7a\u95f4\u53ea\u9700\u8981DATETIME \u7c7b\u578b\u7684\u4e00\u534a\u3002\u5bf9\u4e8e\u53ea\u9700\u8981\u7cbe\u786e\u5230\u67d0\u4e00\u5929\u7684\u6570\u636e\u7c7b\u578b\uff0c\u5efa\u8bae\u4f7f\u7528DATE\u7c7b\u578b\uff0c\u56e0\u4e3a\u4ed6\u7684\u5b58\u50a8\u7a7a\u95f4\u53ea\u9700\u89813\u4e2a\u5b57\u8282\uff0c\u6bd4TIMESTAMP\u8fd8\u5c11\u3002\u4e0d\u5efa\u8bae\u901a\u8fc7INT\u7c7b\u578b\u7c7b\u5b58\u50a8\u4e00\u4e2aunix timestamp \u7684\u503c\uff0c\u56e0\u4e3a\u8fd9\u592a\u4e0d\u76f4\u89c2\uff0c\u4f1a\u7ed9\u7ef4\u62a4\u5e26\u6765\u4e0d\u5fc5\u8981\u7684\u9ebb\u70e6\uff0c\u540c\u65f6\u8fd8\u4e0d\u4f1a\u5e26\u6765\u4efb\u4f55\u597d\u5904\u3002<\/li>\n<li>ENUM &amp;SET\uff1a\u5bf9\u4e8e\u72b6\u6001\u5b57\u6bb5\uff0c\u53ef\u4ee5\u5c1d\u8bd5\u4f7f\u7528 ENUM \u6765\u5b58\u653e\uff0c\u56e0\u4e3a\u53ef\u4ee5\u6781\u5927\u7684\u964d\u4f4e\u5b58\u50a8\u7a7a\u95f4\uff0c\u800c\u4e14\u5373\u4f7f\u9700\u8981\u589e\u52a0\u65b0\u7684\u7c7b\u578b\uff0c\u53ea\u8981\u589e\u52a0\u4e8e\u672b\u5c3e\uff0c\u4fee\u6539\u7ed3\u6784\u4e5f\u4e0d\u9700\u8981\u91cd\u5efa\u8868\u6570\u636e\u3002<\/li>\n<\/ul>\n<p>(2) \u5b57\u7b26\u7f16\u7801<\/p>\n<p>\u5b57\u7b26\u96c6\u76f4\u63a5\u51b3\u5b9a\u4e86\u6570\u636e\u5728MySQL\u4e2d\u7684\u5b58\u50a8\u7f16\u7801\u65b9\u5f0f\uff0c\u7531\u4e8e\u540c\u6837\u7684\u5185\u5bb9\u4f7f\u7528\u4e0d\u540c\u5b57\u7b26\u96c6\u8868\u793a\u6240\u5360\u7528\u7684\u7a7a\u95f4\u5927\u5c0f\u4f1a\u6709\u8f83\u5927\u7684\u5dee\u5f02\uff0c\u6240\u4ee5\u901a\u8fc7\u4f7f\u7528\u5408\u9002\u7684\u5b57\u7b26\u96c6\uff0c\u53ef\u4ee5\u5e2e\u52a9\u6211\u4eec\u5c3d\u53ef\u80fd\u51cf\u5c11\u6570\u636e\u91cf\uff0c\u8fdb\u800c\u51cf\u5c11IO\u64cd\u4f5c\u6b21\u6570\u3002<\/p>\n<p>(3) \u5c3d\u91cf\u4f7f\u7528 NOT NULL<\/p>\n<p>NULL \u7c7b\u578b\u6bd4\u8f83\u7279\u6b8a\uff0cSQL \u96be\u4f18\u5316\u3002\u867d\u7136 MySQL NULL\u7c7b\u578b\u548c Oracle \u7684NULL\u6709\u5dee\u5f02\uff0c\u4f1a\u8fdb\u5165\u7d22\u5f15\u4e2d\uff0c\u4f46\u5982\u679c\u662f\u4e00\u4e2a\u7ec4\u5408\u7d22\u5f15\uff0c\u90a3\u4e48\u8fd9\u4e2aNULL \u7c7b\u578b\u7684\u5b57\u6bb5\u4f1a\u6781\u5927\u5f71\u54cd\u6574\u4e2a\u7d22\u5f15\u7684\u6548\u7387\u3002\u867d\u7136 NULL\u7a7a\u95f4\u4e0a\u53ef\u80fd\u786e\u5b9e\u6709\u4e00\u5b9a\u8282\u7701\uff0c\u5012\u662f\u5e26\u6765\u4e86\u5f88\u591a\u5176\u4ed6\u7684\u4f18\u5316\u95ee\u9898\uff0c\u4e0d\u4f46\u6ca1\u6709\u5c06IO\u91cf\u7701\u4e0b\u6765\uff0c\u53cd\u800c\u52a0\u5927\u4e86SQL\u7684IO\u91cf\u3002\u6240\u4ee5\u5c3d\u91cf\u786e\u4fdd DEFAULT \u503c\u4e0d\u662f NULL\uff0c\u4e5f\u662f\u4e00\u4e2a\u5f88\u597d\u7684\u8868\u7ed3\u6784\u8bbe\u8ba1\u4f18\u5316\u4e60\u60ef\u3002<\/p>\n<h4>3. \u6570\u636e\u5e93\u67b6\u6784\u4f18\u5316<\/h4>\n<p>\u5206\u5e03\u5f0f\u548c\u96c6\u7fa4\u5316\uff1a<\/p>\n<ul>\n<li>\u8d1f\u8f7d\u5747\u8861\u3002\u8d1f\u8f7d\u5747\u8861\u96c6\u7fa4\u662f\u7531\u4e00\u7ec4\u76f8\u4e92\u72ec\u7acb\u7684\u8ba1\u7b97\u673a\u7cfb\u7edf\u6784\u6210\uff0c\u901a\u8fc7\u5e38\u89c4\u7f51\u7edc\u6216\u4e13\u7528\u7f51\u7edc\u8fdb\u884c\u8fde\u63a5\uff0c\u7531\u8def\u7531\u5668\u8854\u63a5\u5728\u4e00\u8d77\uff0c\u5404\u8282\u70b9\u76f8\u4e92\u534f\u4f5c\u3001\u5171\u540c\u8d1f\u8f7d\u3001\u5747\u8861\u538b\u529b\uff0c\u5bf9\u5ba2\u6237\u7aef\u6765\u8bf4\uff0c\u6574\u4e2a\u7fa4\u96c6\u53ef\u4ee5\u89c6\u4e3a\u4e00\u53f0\u5177\u6709\u8d85\u9ad8\u6027\u80fd\u7684\u72ec\u7acb\u670d\u52a1\u5668\u3002MySQL\u4e00\u822c\u90e8\u7f72\u7684\u662f\u9ad8\u53ef\u7528\u6027\u8d1f\u8f7d\u5747\u8861\u96c6\u7fa4\uff0c\u5177\u5907\u8bfb\u5199\u5206\u79bb\uff0c\u4e00\u822c\u53ea\u5bf9\u8bfb\u8fdb\u884c\u8d1f\u8f7d\u5747\u8861\u3002<\/li>\n<li>\u8bfb\u5199\u5206\u79bb\u3002\u8bfb\u5199\u5206\u79bb\u7b80\u5355\u7684\u8bf4\u662f\u628a\u5bf9\u6570\u636e\u5e93\u8bfb\u548c\u5199\u7684\u64cd\u4f5c\u5206\u5f00\u5bf9\u5e94\u4e0d\u540c\u7684\u6570\u636e\u5e93\u670d\u52a1\u5668\uff0c\u8fd9\u6837\u80fd\u6709\u6548\u5730\u51cf\u8f7b\u6570\u636e\u5e93\u538b\u529b\uff0c\u4e5f\u80fd\u51cf\u8f7bio\u538b\u529b\u3002\u4e3b\u6570\u636e\u5e93\u63d0\u4f9b\u5199\u64cd\u4f5c\uff0c\u4ece\u6570\u636e\u5e93\u63d0\u4f9b\u8bfb\u64cd\u4f5c\uff0c\u5176\u5b9e\u5728\u5f88\u591a\u7cfb\u7edf\u4e2d\uff0c\u4e3b\u8981\u662f\u8bfb\u7684\u64cd\u4f5c\u3002\u5f53\u4e3b\u6570\u636e\u5e93\u8fdb\u884c\u5199\u64cd\u4f5c\u65f6\uff0c\u6570\u636e\u8981\u540c\u6b65\u5230\u4ece\u7684\u6570\u636e\u5e93\uff0c\u8fd9\u6837\u624d\u80fd\u6709\u6548\u4fdd\u8bc1\u6570\u636e\u5e93\u5b8c\u6574\u6027\u3002<\/li>\n<li>\u6570\u636e\u5207\u5206\u3002\u901a\u8fc7\u67d0\u79cd\u7279\u5b9a\u7684\u6761\u4ef6\uff0c\u5c06\u5b58\u653e\u5728\u540c\u4e00\u4e2a\u6570\u636e\u5e93\u4e2d\u7684\u6570\u636e\u5206\u6563\u5b58\u653e\u5230\u591a\u4e2a\u6570\u636e\u5e93\u4e0a\uff0c\u5b9e\u73b0\u5206\u5e03\u5b58\u50a8\uff0c\u901a\u8fc7\u8def\u7531\u89c4\u5219\u8def\u7531\u8bbf\u95ee\u7279\u5b9a\u7684\u6570\u636e\u5e93\uff0c\u8fd9\u6837\u4e00\u6765\u6bcf\u6b21\u8bbf\u95ee\u9762\u5bf9\u7684\u5c31\u4e0d\u662f\u5355\u53f0\u670d\u52a1\u5668\u4e86\uff0c\u800c\u662fN\u53f0\u670d\u52a1\u5668\uff0c\u8fd9\u6837\u5c31\u53ef\u4ee5\u964d\u4f4e\u5355\u53f0\u673a\u5668\u7684\u8d1f\u8f7d\u538b\u529b\u3002<\/li>\n<\/ul>\n<h4>4. \u5176\u4ed6\u4f18\u5316<\/h4>\n<p>(1) \u9002\u5f53\u4f7f\u7528\u89c6\u56fe\u52a0\u901f\u67e5\u8be2\u3002<\/p>\n<p>\u628a\u8868\u7684\u4e00\u4e2a\u5b50\u96c6\u8fdb\u884c\u6392\u5e8f\u5e76\u521b\u5efa\u89c6\u56fe\uff0c\u6709\u65f6\u80fd\u52a0\u901f\u67e5\u8be2(\u7279\u522b\u662f\u8981\u88ab\u591a\u6b21\u6267\u884c\u7684\u67e5\u8be2)\u3002\u5b83\u6709\u52a9\u4e8e\u907f\u514d\u591a\u91cd\u6392\u5e8f\u64cd\u4f5c\uff0c\u800c\u4e14\u5728\u5176\u4ed6\u65b9\u9762\u8fd8\u80fd\u7b80\u5316\u4f18\u5316\u5668\u7684\u5de5\u4f5c\u3002\u89c6\u56fe\u4e2d\u7684\u884c\u8981\u6bd4\u4e3b\u8868\u4e2d\u7684\u884c\u5c11\uff0c\u800c\u4e14\u7269\u7406\u987a\u5e8f\u5c31\u662f\u6240\u8981\u6c42\u7684\u987a\u5e8f\uff0c\u51cf\u5c11\u4e86\u78c1\u76d8I\/O\uff0c\u6240\u4ee5\u67e5\u8be2\u5de5\u4f5c\u91cf\u53ef\u4ee5\u5f97\u5230\u5927\u5e45\u51cf\u5c11\u3002<\/p>\n<p>(2) 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