{"id":2394,"date":"2022-12-29T17:14:32","date_gmt":"2022-12-29T09:14:32","guid":{"rendered":"http:\/\/dba.qishuo.xin\/?p=2394"},"modified":"2023-04-17T11:33:01","modified_gmt":"2023-04-17T03:33:01","slug":"%e6%95%b0%e6%8d%ae%e5%ba%93%e5%91%bd%e5%90%8d%e4%b8%8e%e8%ae%be%e8%ae%a1%e8%a7%84%e7%ba%a6","status":"publish","type":"post","link":"http:\/\/dba.qishuo.xin\/?p=2394","title":{"rendered":"\u6570\u636e\u5e93\u547d\u540d\u4e0e\u8bbe\u8ba1\u89c4\u7ea6"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_76 ez-toc-wrap-right counter-hierarchy ez-toc-counter ez-toc-light-blue ez-toc-container-direction\">\n<label for=\"ez-toc-cssicon-toggle-item-69e19f63ca717\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/label><input type=\"checkbox\"  id=\"ez-toc-cssicon-toggle-item-69e19f63ca717\" checked aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#1_%E8%AE%BE%E8%AE%A1%E8%A7%84%E7%BA%A6\" >1. \u8bbe\u8ba1\u89c4\u7ea6<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#11_%E8%A1%A8%E8%AE%BE%E8%AE%A1%E8%A7%84%E7%BA%A6\" >1.1. \u8868\u8bbe\u8ba1\u89c4\u7ea6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#12_%E5%AD%97%E6%AE%B5%E8%AE%BE%E8%AE%A1%E8%A7%84%E7%BA%A6\" >1.2. \u5b57\u6bb5\u8bbe\u8ba1\u89c4\u7ea6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#13_%E7%B4%A2%E5%BC%95%E8%AE%BE%E8%AE%A1%E8%A7%84%E7%BA%A6\" >1.3. \u7d22\u5f15\u8bbe\u8ba1\u89c4\u7ea6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#14_%E6%80%A7%E8%83%BD%E4%BC%98%E5%8C%96\" >1.4. \u6027\u80fd\u4f18\u5316<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#2_%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\" >2. \u547d\u540d\u89c4\u7ea6<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#21_%E6%80%BB%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\" >2.1. \u603b\u547d\u540d\u89c4\u7ea6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#22_%E8%A1%A8%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\" >2.2. \u8868\u547d\u540d\u89c4\u7ea6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#23_%E5%AD%97%E6%AE%B5%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\" >2.3. \u5b57\u6bb5\u547d\u540d\u89c4\u7ea6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#24_%E7%BA%A6%E6%9D%9F%E4%B8%8E%E7%B4%A2%E5%BC%95%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\" >2.4. \u7ea6\u675f\u4e0e\u7d22\u5f15\u547d\u540d\u89c4\u7ea6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#25_%E5%85%B6%E4%BB%96%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\" >2.5. \u5176\u4ed6\u547d\u540d\u89c4\u7ea6<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#3_SQL%E8%A7%84%E7%BA%A6\" >3. SQL\u89c4\u7ea6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#%E9%99%84%E5%BD%95\" >\u9644\u5f55<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#%E9%99%84%E5%BD%95A_%E7%9B%B8%E5%85%B3%E8%81%94%E7%9A%84%E6%96%87%E7%AB%A0\" >\u9644\u5f55A. \u76f8\u5173\u8054\u7684\u6587\u7ae0<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#%E9%99%84%E5%BD%95B_%E5%85%B6%E4%BB%96%E5%8F%82%E8%80%83\" >\u9644\u5f55B. \u5176\u4ed6\u53c2\u8003<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#%E9%99%84%E5%BD%95C_%E6%95%B0%E6%8D%AE%E5%BA%93%E8%AE%BE%E8%AE%A1%E4%B8%89%E8%8C%83%E5%BC%8F\" >\u9644\u5f55C. \u6570\u636e\u5e93\u8bbe\u8ba1\u4e09\u8303\u5f0f<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"http:\/\/dba.qishuo.xin\/?p=2394\/#%E9%99%84%E5%BD%95D_MySQL%E5%94%AF%E4%B8%80%E7%B4%A2%E5%BC%95%E7%BA%A6%E6%9D%9F\" >\u9644\u5f55D. MySQL\u552f\u4e00\u7d22\u5f15\u7ea6\u675f<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<p><strong>\u8bf4\u660e\uff1a\u672c\u6587\u53c2\u8003\u963f\u91cc\u5df4\u5df4Java\u5f00\u53d1\u624b\u518c\uff0c\u4ee5MySQL\u8bed\u6cd5\u4e3a\u4e3b\u3001Oracle\u8bed\u6cd5\u4e3a\u8f85\u505a\u4e3a\u793a\u4f8b\u64b0\u5199\u3002<\/strong><\/p>\n<h3><span class=\"ez-toc-section\" id=\"1_%E8%AE%BE%E8%AE%A1%E8%A7%84%E7%BA%A6\"><\/span>1. \u8bbe\u8ba1\u89c4\u7ea6<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<h4><span class=\"ez-toc-section\" id=\"11_%E8%A1%A8%E8%AE%BE%E8%AE%A1%E8%A7%84%E7%BA%A6\"><\/span>1.1. \u8868\u8bbe\u8ba1\u89c4\u7ea6<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ol>\n<li>\n<p>\u9075\u5b88\u6570\u636e\u7684\u8bbe\u8ba1\u89c4\u8303 3NF \u89c4\u5b9a\u3002<br \/>\n\u53c2\u89c1\uff1a<a target=\"_blank\" href=\"#\u9644\u5f55\">\u9644\u5f55<\/a><\/p>\n<\/li>\n<li>\n<p>\u8868\u7684\u5b57\u6bb5\u6570\u4e0d\u8d85\u8fc730\u4e2a\uff0c\u5982\u679c\u8d85\u8fc7\u8be5\u503c\uff0c\u53ef\u4ee5\u6839\u636e\u4e1a\u52a1\u60c5\u51b5\u8fdb\u884c\u62c6\u5206\uff0c\u6bd4\u5982\u6839\u636e\u5e38\u7528\u5b57\u6bb5\u548c\u975e\u5e38\u7528\u5b57\u6bb5\u5c06\u4e00\u5f20\u8868\u62c6\u5206\u6210\u4e24\u5f20\uff1b\u4e5f\u53ef\u4ee5\u6839\u636e\u7528\u9014\u3001\u914d\u7f6e\u7b49\u5206\u6210\u4e0d\u540c\u7684\u8868\u3002<\/p>\n<\/li>\n<li>\n<p>\u91c7\u7528UTF8\u5b57\u7b26\u96c6\u6216UTF8mb4\u5b57\u7b26\u96c6\u3002<\/p>\n<\/li>\n<li>\n<p>\u5355\u8868\u884c\u6570\u8d85\u8fc7 500 \u4e07\u884c\u6216\u8005\u5355\u8868\u5bb9\u91cf\u8d85\u8fc7 2GB\uff0c\u624d\u63a8\u8350\u8fdb\u884c\u5206\u5e93\u5206\u8868\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u5982\u679c\u9884\u8ba1\u4e09\u5e74\u540e\u7684\u6570\u636e\u91cf\u6839\u672c\u8fbe\u4e0d\u5230\u8fd9\u4e2a\u7ea7\u522b\uff0c\u8bf7\u4e0d\u8981\u5728\u521b\u5efa\u8868\u65f6\u5c31\u5206\u5e93\u5206\u8868\u3002<\/p>\n<\/li>\n<li>\n<p>\u5b57\u6bb5\u5141\u8bb8\u9002\u5f53\u5197\u4f59\uff0c\u4ee5\u63d0\u9ad8\u67e5\u8be2\u6027\u80fd\uff0c\u4f46\u5fc5\u987b\u8003\u8651\u6570\u636e\u4e00\u81f4\u3002\u5197\u4f59\u5b57\u6bb5\u5e94\u9075\u5faa\uff1a<\/p>\n<ul>\n<li>\u4e0d\u662f\u9891\u7e41\u4fee\u6539\u7684\u5b57\u6bb5\u3002<\/li>\n<li>\u4e0d\u662f\u552f\u4e00\u7d22\u5f15\u7684\u5b57\u6bb5\u3002<\/li>\n<li>\u4e0d\u662f varchar \u8d85\u957f\u5b57\u6bb5\uff0c\u66f4\u4e0d\u80fd\u662f text \u5b57\u6bb5\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span>\u5404\u4e1a\u52a1\u7ebf\u7ecf\u5e38\u5197\u4f59\u5b58\u50a8\u5546\u54c1\u540d\u79f0\uff0c\u907f\u514d\u67e5\u8be2\u65f6\u9700\u8981\u8c03\u7528 IC \u670d\u52a1\u83b7\u53d6\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u5206\u533a\u8868\u2014\u2014\u5bf9\u4e8e\u6570\u636e\u91cf\u6bd4\u8f83\u5927\u7684\u8868\uff0c\u6839\u636e\u8868\u6570\u636e\u7684\u5c5e\u6027\u8fdb\u884c\u5206\u533a\uff0c\u4ee5\u5f97\u5230\u8f83\u597d\u7684\u6027\u80fd\u3002<br \/>\n\u5982\u679c\u8868\u6309\u67d0\u4e9b\u5b57\u6bb5\u8fdb\u884c\u589e\u957f\uff0c\u5219\u91c7\u7528\u6309\u5b57\u6bb5\u503c\u8303\u56f4\u8fdb\u884c\u8303\u56f4\u5206\u533a\uff1b<br \/>\n\u5982\u679c\u8868\u6309\u67d0\u4e2a\u5b57\u6bb5\u7684\u51e0\u4e2a\u5173\u952e\u503c\u8fdb\u884c\u5206\u5e03,\u5219\u91c7\u7528\u5217\u8868\u5206\u533a\uff1b<br \/>\n\u5bf9\u4e8e\u9759\u6001\u8868,\u5219\u91c7\u7528 hash \u5206\u533a\u6216\u5217\u8868\u5206\u533a\uff1b<br \/>\n\u5728\u8303\u56f4\u5206\u533a\u4e2d\uff0c\u5982\u679c\u6570\u636e\u6309\u67d0\u5173\u952e\u5b57\u6bb5\u5747\u8861\u5206\u5e03,\u5219\u91c7\u7528\u5b50\u5206\u533a\u7684\u590d\u5408\u5206\u533a\u65b9\u6cd5\u3002<\/p>\n<\/li>\n<\/ol>\n<h4><span class=\"ez-toc-section\" id=\"12_%E5%AD%97%E6%AE%B5%E8%AE%BE%E8%AE%A1%E8%A7%84%E7%BA%A6\"><\/span>1.2. \u5b57\u6bb5\u8bbe\u8ba1\u89c4\u7ea6<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ol>\n<li>\n<p>\u51e1\u662f\u53ef\u80fd\u88ab\u7d22\u5f15\u7684\u5b57\u6bb5,\u5fc5\u987b\u5b9a\u4e49\u4e3aNOT NULL,\u53ef\u4ee5\u8bbe\u7f6edefault\u503c\u3002<\/p>\n<\/li>\n<li>\n<p>\u975e\u8d1f\u503c\u7684\u6570\u5b57\u7edf\u4e00\u4f7f\u7528 <code>unsigned\uff08\u65e0\u7b26\u53f7\uff09<\/code> \u7c7b\u578b\u5b58\u50a8\u3002<\/p>\n<\/li>\n<li>\n<p>\u5927\u5bf9\u8c61\u5b57\u6bb5<\/p>\n<ul>\n<li>\u901a\u5e38\u60c5\u51b5\u4e0b\uff0c\u7981\u6b62\u4f7f\u7528LOB\u7c7b\u578b\u4fdd\u5b58\u5927\u6587\u672c\u3001\u56fe\u7247\u548c\u6587\u4ef6,\u5efa\u8bae\u4f7f\u7528\u5176\u4ed6\u65b9\u5f0f\u5b58\u50a8\uff08\u4f8b\u5982\u6587\u4ef6\u7cfb\u7edf,\u6570\u636e\u5e93\u53ea\u4fdd\u5b58\u5176\u5730\u5740\u4fe1\u606f\uff09\u3002<\/li>\n<li>MySQL\uff1a\u5c3d\u91cf\u4e0d\u8981\u4f7f\u7528TEXT\u6570\u636e\u7c7b\u578b\uff0cmysql\u7684varchar\u7c7b\u578b\u652f\u630165535\u5b57\u8282\uff0c\u6ee1\u8db3\u5927\u591a\u6570\u573a\u666f\uff0c\u4ec5\u5f53\u5b57\u7b26\u6570\u7279\u522b\u5927\u65f6,\u624d\u8003\u8651text\u7c7b\u578b\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u7981\u6b62\u4f7f\u7528enum,\u5bf9\u4e8eboolean\u7c7b\u578b\u6216\u8005\u8868\u793a\u7b80\u5355\u72b6\u6001\u7684\u5b57\u6bb5,MySQL\u7528 <code>tinyint<\/code>,Oracle\u7528<code>NUMBER(1)<\/code><\/p>\n<ul>\n<li>\u5efa\u8bae\u5b57\u6bb5not null,\u6839\u636e\u4e1a\u52a1\u8981\u6c42\u6765\u8bbe\u7f6e\u9ed8\u8ba4\u503c\uff08\u4f8b\u5982\u9ed8\u8ba4\u4e3a0\uff09\u3002<\/li>\n<li>\u5bf9\u4e8eboolean\u7c7b\u578b,\u4ee51\u4ee3\u8868\u662f\uff08true\uff09, 0 \u4ee3\u8868\u5426\uff08false\uff09\u3002<\/li>\n<li>\u5bf9\u4e8e\u72b6\u6001\u7c7b\u578b\uff0c\u6ce8\u91ca\u4e2d\u5e94\u8be5\u6ce8\u660e\u6bcf\u4e00\u79cd\u72b6\u6001\u7684\u542b\u4e49\uff0c\u4f8b\u5982<code>0\uff1a\u7f16\u8f91\u4e2d,1\uff1a\u5ba1\u6838\u4e2d,2\uff1a\u5df2\u5b8c\u6210<\/code>\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u6570\u5b57\u3001\u5c0f\u6570\u7c7b\u578b<\/p>\n<ul>\n<li>\u5bf9\u4e8e\u6570\u5b57\u3001\u5c0f\u6570\u7c7b\u578b\uff0c\u4e0d\u5f97\u4f7f\u7528VACHAR\u7b49\u5b57\u7b26\u4e32\u7c7b\u578b\u6765\u4fdd\u5b58\uff0c\u5e94\u8be5\u4f7f\u7528\u76f8\u5e94\u7cbe\u5ea6\u7684\u6570\u5b57\u3001\u5c0f\u6570\u7c7b\u578b\u3002<\/li>\n<li>\u5c3d\u91cf\u786e\u4fdd\u6570\u503c\u578b\u5217\u90fd\u6709\u9ed8\u8ba4\u503c\u3002<\/li>\n<li>\u5bf9\u4e8eOracle\uff0c\u786e\u5b9a\u597dNumber\u7684\u7cbe\u5ea6\u3002<\/li>\n<li>\u5bf9\u4e8eMySQL,\u9009\u597d\u6570\u5b57\u7c7b\u578b\uff1aTINYINT &gt; SMALLINT &gt; MEDIUMINT &gt; INT &gt; BIGINT &gt; DECIMAL(\u5b58\u50a8\u7a7a\u95f4\u9010\u6e10\u53d8\u5927,\u800c\u6027\u80fd\u5374\u9010\u6e10\u53d8\u5c0f),\u8d85\u8fc7 <code>tinyint\uff08256\uff09<\/code> \u4f46\u4e0d\u8d85\u8fc7 65536 \u7684\u4f7f\u7528smallint\uff1b\u5f53\u8be5\u5b57\u6bb5\u8d85\u8fc742\u4ebf\u65f6,\u624d\u4f7f\u7528bigint\uff1b<br \/>\n<a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/12\/image-1672214047131.png\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/12\/image-1672214047131.png\" alt=\"file\" \/><\/a><\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u65f6\u95f4\u7c7b\u578b\u6807\u51c6<\/p>\n<ul>\n<li>Oracle\u6709\u4e24\u79cd\u65f6\u95f4\u7c7b\u578b\uff1a<code>DATE\u548cTIMESTAMP<\/code>,DATE\u7684\u7cbe\u5ea6\u53ea\u4fdd\u5b58\u5230\u79d2,\u4f8b\u5982<code>2013-11-02 11:16:36<\/code>\uff0c\u800cTIMESTAMP\u7cbe\u5ea6\u66f4\u9ad8\u53ef\u4ee5\u4fdd\u5b58\u5c0f\u6570\u79d2\uff0c\u4f8b\u5982<code>2013-11-03 11:16:36.000000<\/code> \u3002\u6709\u65f6\u5019 DATE \u53ea\u4fdd\u5b58\u5230\u79d2,\u4e0d\u8db3\u591f\u533a\u522b\u51fa\u4e24\u4e2a\u4e8b\u4ef6\u54ea\u4e2a\u5148\u53d1\u751f\uff0c\u8fd9\u65f6\u5efa\u8bae\u4f7f\u7528TIMESTAMP\u7c7b\u578b\u3002<\/li>\n<li>MySQL\u5b58\u50a8\u5e74\u4f7f\u7528year\u7c7b\u578b\uff0c\u4ec5\u5b58\u50a8\u65e5\u671f\u4f7f\u7528date\u7c7b\u578b\uff1b\u5b58\u50a8\u5e26\u65f6\u95f4\u7684\u65e5\u671f\u65f6\u4f7f\u7528datetime\u7c7b\u578b\uff1b\u4f7f\u7528\u7cbe\u786e\u65f6\u95f4\u6233\uff08\u7cbe\u786e\u5230\u79d2\uff09\u5c3d\u91cf\u4f7f\u7528timestamp\u7c7b\u578b,\u56e0\u4e3atimestamp\u4f7f\u75284\u5b57\u8282,datetime\u4f7f\u75288\u5b57\u8282,\u5b83\u4eec\u7684\u533a\u522b\uff1aTIMESTAMP\u503c\u4e0d\u80fd\u65e9\u4e8e1970\u6216\u665a\u4e8e2037\uff08<code>1970-01-01 00:00:01<\/code> UTC to <code>2038-01-19 03:14:07<\/code> UTC\uff09\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<h4><span class=\"ez-toc-section\" id=\"13_%E7%B4%A2%E5%BC%95%E8%AE%BE%E8%AE%A1%E8%A7%84%E7%BA%A6\"><\/span>1.3. \u7d22\u5f15\u8bbe\u8ba1\u89c4\u7ea6<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ol>\n<li>\n<p>\u4e1a\u52a1\u4e0a\u5177\u6709\u552f\u4e00\u7279\u6027\u7684\u5b57\u6bb5\uff0c\u5373\u4f7f\u662f\u7ec4\u5408\u5b57\u6bb5\uff0c\u4e5f\u5fc5\u987b\u5efa\u6210\u552f\u4e00\u7d22\u5f15\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u4e0d\u8981\u4ee5\u4e3a\u552f\u4e00\u7d22\u5f15\u5f71\u54cd\u4e86 insert \u901f\u5ea6\uff0c\u8fd9\u4e2a\u901f\u5ea6\u635f\u8017\u53ef\u4ee5\u5ffd\u7565\uff0c\u4f46\u63d0\u9ad8\u67e5\u627e\u901f\u5ea6\u662f\u660e\u663e\u7684\uff1b\u53e6\u5916\uff0c\u5373\u4f7f\u5728\u5e94\u7528\u5c42\u505a\u4e86\u975e\u5e38\u5b8c\u5584\u7684\u6821\u9a8c\u63a7\u5236\uff0c\u53ea\u8981\u6ca1\u6709\u552f\u4e00\u7d22\u5f15\uff0c\u6839\u636e\u58a8\u83f2\u5b9a\u5f8b\uff0c\u5fc5\u7136\u6709\u810f\u6570\u636e\u4ea7\u751f\u3002<\/p>\n<\/li>\n<li>\n<p>\u5728 varchar \u5b57\u6bb5\u4e0a\u5efa\u7acb\u7d22\u5f15\u65f6\uff0c\u5fc5\u987b\u6307\u5b9a\u7d22\u5f15\u957f\u5ea6\uff0c\u6ca1\u5fc5\u8981\u5bf9\u5168\u5b57\u6bb5\u5efa\u7acb\u7d22\u5f15\uff0c\u6839\u636e\u5b9e\u9645\u6587\u672c\u533a\u5206\u5ea6\u51b3\u5b9a\u7d22\u5f15\u957f\u5ea6\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u7d22\u5f15\u7684\u957f\u5ea6\u4e0e\u533a\u5206\u5ea6\u662f\u4e00\u5bf9\u77db\u76fe\u4f53\uff0c\u4e00\u822c\u5bf9\u5b57\u7b26\u4e32\u7c7b\u578b\u6570\u636e\uff0c\u957f\u5ea6\u4e3a 20 \u7684\u7d22\u5f15\uff0c\u533a\u5206\u5ea6\u4f1a\u9ad8\u8fbe 90%\u4ee5\u4e0a\uff0c\u53ef\u4ee5\u4f7f\u7528 <code>count(distinct left(\u5217\u540d, \u7d22\u5f15\u957f\u5ea6))\/count(*)<\/code> \u7684\u533a\u5206\u5ea6\u6765\u786e\u5b9a\u3002<\/p>\n<\/li>\n<li>\n<p>\u5728\u5206\u533a\u8868\u4e2d\u4e0d\u5efa\u8bae\u4f7f\u7528\u5168\u5c40\u7d22\u5f15\uff0c\u56e0\u4e3a\u505a\u5206\u533a\u7ef4\u62a4\u64cd\u4f5c\u65f6\u53ef\u80fd\u4f1a\u5bfc\u81f4\u5168\u5c40\u7d22\u5f15\u5931\u6548\uff0c\u9020\u6210\u96be\u4ee5\u7ef4\u62a4\u3002<\/p>\n<\/li>\n<li>\n<p>\u5355\u8868\u7684\u7d22\u5f15\u6570\u91cf\u5c3d\u91cf\u63a7\u5236\u57285\u4e2a\u4ee5\u5185\uff0c\u5355\u4e2a\u5b57\u6bb5\u4e0a\u7684\u7d22\u5f15\u4e0d\u80fd\u8d85\u8fc72\u4e2a\u3002<\/p>\n<\/li>\n<li>\n<p>Order by\u3001distinct\u3001group by\u540e\u7684\u5b57\u6bb5\u5c3d\u91cf\u5efa\u7acb\u7d22\u5f15\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u5982\u679c\u6709 order by \u7684\u573a\u666f\uff0c\u8bf7\u6ce8\u610f\u5229\u7528\u7d22\u5f15\u7684\u6709\u5e8f\u6027\u3002order by \u6700\u540e\u7684\u5b57\u6bb5\u662f\u7ec4\u5408\u7d22\u5f15\u7684\u4e00\u90e8\u5206\uff0c\u5e76\u4e14\u653e\u5728\u7d22\u5f15\u7ec4\u5408\u987a\u5e8f\u7684\u6700\u540e\uff0c\u907f\u514d\u51fa\u73b0 <code>file_sort<\/code> \u7684\u60c5\u51b5\uff0c\u5f71\u54cd\u67e5\u8be2\u6027\u80fd\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span>where a=? and b=? order by c; \u7d22\u5f15\uff1aa_b_c<br \/>\n<span style='color:#ff7e66'><strong>\u53cd\u4f8b\uff1a<\/strong><\/span>\u7d22\u5f15\u5982\u679c\u5b58\u5728\u8303\u56f4\u67e5\u8be2\uff0c\u90a3\u4e48\u7d22\u5f15\u6709\u5e8f\u6027\u65e0\u6cd5\u5229\u7528\uff0c\u5982\uff1aWHERE a&gt;10 ORDER BY b; \u7d22\u5f15 a_b \u65e0\u6cd5\u6392\u5e8f\u3002<\/p>\n<\/li>\n<li>\n<p>\u5229\u7528\u8986\u76d6\u7d22\u5f15\u6765\u8fdb\u884c\u67e5\u8be2\u64cd\u4f5c\uff0c\u907f\u514d\u56de\u8868\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u5982\u679c\u4e00\u672c\u4e66\u9700\u8981\u77e5\u9053\u7b2c 11 \u7ae0\u662f\u4ec0\u4e48\u6807\u9898\uff0c\u4f1a\u7ffb\u5f00\u7b2c 11 \u7ae0\u5bf9\u5e94\u7684\u90a3\u4e00\u9875\u5417\uff1f\u76ee\u5f55\u6d4f\u89c8\u4e00\u4e0b\u5c31\u597d\uff0c\u8fd9\u4e2a\u76ee\u5f55\u5c31\u662f\u8d77\u5230\u8986\u76d6\u7d22\u5f15\u7684\u4f5c\u7528\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span>\u80fd\u591f\u5efa\u7acb\u7d22\u5f15\u7684\u79cd\u7c7b\u5206\u4e3a\u4e3b\u952e\u7d22\u5f15\u3001\u552f\u4e00\u7d22\u5f15\u3001\u666e\u901a\u7d22\u5f15\u4e09\u79cd\uff0c\u800c\u8986\u76d6\u7d22\u5f15\u53ea\u662f\u4e00\u79cd\u67e5\u8be2\u7684\u4e00\u79cd\u6548\u679c\uff0c\u7528 explain \u7684\u7ed3\u679c\uff0cextra \u5217\u4f1a\u51fa\u73b0\uff1a<code>using index<\/code>\u3002<\/p>\n<\/li>\n<li>\n<p>update\u3001delete\u7684where\u5c3d\u91cf\u4f7f\u7528\u6709\u7d22\u5f15\u7684\u5b57\u6bb5\u6216\u4e3b\u952e\u3002<\/p>\n<\/li>\n<li>\n<p>\u4e0d\u5efa\u8bae\u5728\u4f4e\u57fa\u6570\u5217\u4e0a(\u7c7b\u4f3c\u4e8e\u6570\u636e\u5b57\u5178\u5217)\u521b\u5efa\u7d22\u5f15,\u4f8b\u5982<code>\u6027\u522b<\/code>\u5217\u3002<\/p>\n<\/li>\n<li>\n<p>\u9ad8\u5e76\u53d1\u8868\u7684\u7d22\u5f15\u8bbe\u8ba1\uff0c\u5e94\u907f\u514d\u7d22\u5f15\u5b57\u6bb5\u91c7\u7528\u5355\u5e8f\u5217\u751f\u6210\uff0c\u5426\u5219\u5bb9\u6613\u4ea7\u751f\u7d22\u5f15\u4e89\u7528\uff0c\u964d\u4f4e\u6570\u636e\u63d2\u5165\u6548\u7387\u3002<\/p>\n<\/li>\n<li>\n<p>\u7ecf\u5e38\u4e0e\u5176\u4ed6\u8868\u8fdb\u884c\u8fde\u63a5\u7684\u8868,\u5728\u8fde\u63a5\u5b57\u6bb5\u4e0a\u5e94\u8be5\u5efa\u7acb\u7d22\u5f15\u3002<\/p>\n<\/li>\n<li>\n<p>\u7ecf\u5e38\u51fa\u73b0\u5728 Where \u5b50\u53e5\u4e2d\u7684\u5b57\u6bb5\u4e14\u8fc7\u6ee4\u6027\u5f88\u5f3a\u7684,\u7279\u522b\u662f\u5927\u8868\u7684\u5b57\u6bb5,\u5e94\u8be5\u5efa\u7acb\u7d22\u5f15\u3002<\/p>\n<\/li>\n<li>\n<p>\u590d\u5408\u7d22\u5f15\u7684\u5efa\u7acb\u9700\u8981\u8fdb\u884c\u4ed4\u7ec6\u5206\u6790<\/p>\n<ul>\n<li>\u590d\u5408\u7d22\u5f15\u7684\u5b57\u6bb5\u6570\u4e0d\u80fd\u8d85\u8fc75\u4e2a\uff0c\u5e76\u5408\u7406\u521b\u5efa\u8054\u5408\u7d22\u5f15\uff08\u907f\u514d\u5197\u4f59\uff09,(a,b,c) \u76f8\u5f53\u4e8e\uff08a\uff09\u3001\uff08a\u3001b\uff09\u3001\uff08a\u3001b\u3001c\uff09;<\/li>\n<li>\u6b63\u786e\u9009\u62e9\u590d\u5408\u7d22\u5f15\u4e2d\u7684\u7b2c\u4e00\u4e2a\u5b57\u6bb5,\u4e00\u822c\u662f\u9009\u62e9\u6027\u8f83\u597d\u7684\u4e14\u5728where\u5b50\u53e5\u4e2d\u5e38\u7528\u7684\u5b57\u6bb5\u4e0a\uff1b<\/li>\n<li>\u590d\u5408\u7d22\u5f15\u7684\u51e0\u4e2a\u5b57\u6bb5\u662f\u5426\u7ecf\u5e38\u540c\u65f6\u4ee5AND\u65b9\u5f0f\u51fa\u73b0\u5728Where\u5b50\u53e5\u4e2d\uff1f\u5355\u5b57\u6bb5\u67e5\u8be2\u662f\u5426\u6781\u5c11\u751a\u81f3\u6ca1\u6709\uff1f\u5982\u679c\u662f,\u5219\u53ef\u4ee5\u5efa\u7acb\u590d\u5408\u7d22\u5f15\uff1b\u5426\u5219\u8003\u8651\u5355\u5b57\u6bb5\u7d22\u5f15\uff1b<\/li>\n<li>\u5982\u679c\u590d\u5408\u7d22\u5f15\u4e2d\u5305\u542b\u7684\u5b57\u6bb5\u7ecf\u5e38\u5355\u72ec\u51fa\u73b0\u5728Where\u5b50\u53e5\u4e2d,\u5219\u5206\u89e3\u4e3a\u591a\u4e2a\u5355\u5b57\u6bb5\u7d22\u5f15\uff1b<\/li>\n<li>\u5982\u679c\u65e2\u6709\u5355\u5b57\u6bb5\u7d22\u5f15,\u53c8\u6709\u4ee5\u8fd9\u4e2a\u5b57\u6bb5\u4e3a\u9996\u5217\u7684\u590d\u5408\u7d22\u5f15,\u4e00\u822c\u53ef\u8003\u8651\u5220\u9664\u5355\u5b57\u6bb5\u7d22\u5f15\uff1b<\/li>\n<li><span style='color:red'>\u590d\u5408\u7d22\u5f15\u7b2c\u4e00\u4e2a\u5b57\u6bb5\u4e00\u822c\u4e0d\u4f7f\u7528\u65f6\u95f4\u5b57\u6bb5\uff0c\u56e0\u4e3a\u65f6\u95f4\u5b57\u6bb5\u591a\u7528\u4e8e\u8303\u56f4\u626b\u63cf\uff0c\u800c\u524d\u9762\u7684\u5b57\u6bb5\u4f7f\u7528\u8303\u56f4\u626b\u63cf\u540e\uff0c\u540e\u7eed\u5b57\u6bb5\u65e0\u6cd5\u7528\u4e8e\u7d22\u5f15\u8fc7\u6ee4\u3002<\/span><\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u5efa\u7ec4\u5408\u7d22\u5f15\u7684\u65f6\u5019\uff0c\u533a\u5206\u5ea6\u6700\u9ad8\u7684\u5728\u6700\u5de6\u8fb9\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span>\u5982\u679c where a=? and b=?\uff0ca \u5217\u7684\u51e0\u4e4e\u63a5\u8fd1\u4e8e\u552f\u4e00\u503c\uff0c\u90a3\u4e48\u53ea\u9700\u8981\u5355\u5efa idx_a \u7d22\u5f15\u5373\u53ef\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u5b58\u5728\u975e\u7b49\u53f7\u548c\u7b49\u53f7\u6df7\u5408\u5224\u65ad\u6761\u4ef6\u65f6\uff0c\u5728\u5efa\u7d22\u5f15\u65f6\uff0c\u8bf7\u628a\u7b49\u53f7\u6761\u4ef6\u7684\u5217\u524d\u7f6e\u3002\u5982\uff1awhere c&gt;? and d=? <span style='color:red'>\u90a3\u4e48\u5373\u4f7f c \u7684\u533a\u5206\u5ea6\u66f4\u9ad8\uff0c\u4e5f\u5fc5\u987b\u628a d \u653e\u5728\u7d22\u5f15\u7684\u6700\u524d\u5217\uff0c\u5373\u5efa\u7acb\u7ec4\u5408\u7d22\u5f15 idx_d_c\u3002<\/span><\/p>\n<\/li>\n<li>\n<p>\u9891\u7e41 DML(\u5199\u6b21\u6570\u660e\u663e\u8d85\u8fc7\u8bfb\u6b21\u6570)\u7684\u8868,\u4e0d\u8981\u5efa\u7acb\u592a\u591a\u7684\u7d22\u5f15\u3002<\/p>\n<\/li>\n<li>\n<p>\u65e0\u7528\u7684\u7d22\u5f15\u4ee5\u53ca\u91cd\u590d\u7d22\u5f15\u5e94\u5220\u9664\uff0c\u907f\u514d\u5bf9\u6267\u884c\u8ba1\u5212\u53ca\u6570\u636e\u5e93\u6027\u80fd\u9020\u6210\u8d1f\u9762\u5f71\u54cd\u3002<\/p>\n<\/li>\n<li>\n<p>OLTP \u7cfb\u7edf\uff0c\u7981\u6b62\u4f7f\u7528\u4f4d\u56fe\u7d22\u5f15\u3002OLAP \u7cfb\u7edf\uff0c\u5bf9\u4e8e\u90e8\u5206\u7ecf\u5e38\u5728\u6761\u4ef6\u4e2d\u51fa\u73b0\uff0c\u4e14\u552f\u4e00\u503c\u4e0d\u5927\u7684\u5b57\u6bb5\uff0c\u53ef\u4ee5\u8003\u8651\u4f7f\u7528\u4f4d\u56fe\u7d22\u5f15\uff0c\u4f46\u662f\u9700\u8981\u6ce8\u610f\u8be5\u8868\u4e0d\u80fd\u8fdb\u884c\u591a\u4e2a\u8fdb\u7a0b\u7684\u540c\u65f6 DML\u3002<\/p>\n<\/li>\n<li>\n<p>\u9632\u6b62\u56e0\u5b57\u6bb5\u7c7b\u578b\u4e0d\u540c\u9020\u6210\u7684\u9690\u5f0f\u8f6c\u6362\uff0c\u5bfc\u81f4\u7d22\u5f15\u5931\u6548\u3002<\/p>\n<\/li>\n<li>\n<p>\u521b\u5efa\u7d22\u5f15\u65f6\u907f\u514d\u6709\u5982\u4e0b\u6781\u7aef\u8bef\u89e3\uff1a<\/p>\n<ul>\n<li>1\uff09 \u7d22\u5f15\u5b81\u6ee5\u52ff\u7f3a\u3002\u8ba4\u4e3a\u4e00\u4e2a\u67e5\u8be2\u5c31\u9700\u8981\u5efa\u4e00\u4e2a\u7d22\u5f15\u3002<\/li>\n<li>2\uff09 \u541d\u556c\u7d22\u5f15\u7684\u521b\u5efa\u3002\u8ba4\u4e3a\u7d22\u5f15\u4f1a\u6d88\u8017\u7a7a\u95f4\u3001\u4e25\u91cd\u62d6\u6162\u8bb0\u5f55\u7684\u66f4\u65b0\u4ee5\u53ca\u884c\u7684\u65b0\u589e\u901f\u5ea6\u3002<\/li>\n<li>3\uff09 \u62b5\u5236\u60df\u4e00\u7d22\u5f15\u3002\u8ba4\u4e3a\u60df\u4e00\u7d22\u5f15\u4e00\u5f8b\u9700\u8981\u5728\u5e94\u7528\u5c42\u901a\u8fc7\u201c\u5148\u67e5\u540e\u63d2\u201d\u65b9\u5f0f\u89e3\u51b3\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<h4><span class=\"ez-toc-section\" id=\"14_%E6%80%A7%E8%83%BD%E4%BC%98%E5%8C%96\"><\/span>1.4. \u6027\u80fd\u4f18\u5316<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ol>\n<li>\n<p>SQL \u6027\u80fd\u4f18\u5316\u7684\u76ee\u6807\uff1a\u81f3\u5c11\u8981\u8fbe\u5230 range \u7ea7\u522b\uff0c\u8981\u6c42\u662f ref \u7ea7\u522b\uff0c\u5982\u679c\u53ef\u4ee5\u662f consts \u6700\u597d\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><br \/>\n1\uff09 consts \u5355\u8868\u4e2d\u6700\u591a\u53ea\u6709\u4e00\u4e2a\u5339\u914d\u884c\uff08\u4e3b\u952e\u6216\u8005\u552f\u4e00\u7d22\u5f15\uff09\uff0c\u5728\u4f18\u5316\u9636\u6bb5\u5373\u53ef\u8bfb\u53d6\u5230\u6570\u636e\u3002<br \/>\n2\uff09 ref \u6307\u7684\u662f\u4f7f\u7528\u666e\u901a\u7684\u7d22\u5f15\uff08normal index\uff09\u3002<br \/>\n3\uff09 range \u5bf9\u7d22\u5f15\u8fdb\u884c\u8303\u56f4\u68c0\u7d22\u3002<br \/>\n<span style='color:#ff7e66'><strong>\u53cd\u4f8b\uff1a<\/strong><\/span>explain \u8868\u7684\u7ed3\u679c\uff0ctype=index\uff0c\u7d22\u5f15\u7269\u7406\u6587\u4ef6\u5168\u626b\u63cf\uff0c\u901f\u5ea6\u975e\u5e38\u6162\uff0c\u8fd9\u4e2a index \u7ea7\u522b\u6bd4\u8f83 range \u8fd8\u4f4e\uff0c\u4e0e\u5168\u8868\u626b\u63cf\u662f\u5c0f\u5deb\u89c1\u5927\u5deb\u3002<\/p>\n<\/li>\n<li>\n<p>\u5229\u7528\u5ef6\u8fdf\u5173\u8054\u6216\u8005\u5b50\u67e5\u8be2\u4f18\u5316\u8d85\u591a\u5206\u9875\u573a\u666f\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>MySQL \u5e76\u4e0d\u662f\u8df3\u8fc7 offset \u884c\uff0c\u800c\u662f\u53d6 offset+N \u884c\uff0c\u7136\u540e\u8fd4\u56de\u653e\u5f03\u524d offset \u884c\uff0c\u8fd4\u56de N \u884c\uff0c\u90a3\u5f53 offset \u7279\u522b\u5927\u7684\u65f6\u5019\uff0c\u6548\u7387\u5c31\u975e\u5e38\u7684\u4f4e\u4e0b\uff0c\u8981\u4e48\u63a7\u5236\u8fd4\u56de\u7684\u603b\u9875\u6570\uff0c\u8981\u4e48\u5bf9\u8d85\u8fc7\u7279\u5b9a\u9608\u503c\u7684\u9875\u6570\u8fdb\u884c SQL \u6539\u5199\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span>\u5148\u5feb\u901f\u5b9a\u4f4d\u9700\u8981\u83b7\u53d6\u7684 id \u6bb5\uff0c\u7136\u540e\u518d\u5173\u8054\uff1a<code>SELECT t1.* FROM \u8868 1 as t1, (select id from \u8868 1 where \u6761\u4ef6 LIMIT 100000,20 ) as t2 where t1.id=t2.id<\/code><\/p>\n<\/li>\n<li>\n<p>\u9875\u9762\u641c\u7d22\u4e25\u7981\u5de6\u6a21\u7cca\u6216\u8005\u5168\u6a21\u7cca\uff0c\u5982\u679c\u9700\u8981\u8bf7\u8d70\u641c\u7d22\u5f15\u64ce\u6765\u89e3\u51b3\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u7d22\u5f15\u6587\u4ef6\u5177\u6709 B-Tree \u7684\u6700\u5de6\u524d\u7f00\u5339\u914d\u7279\u6027\uff0c\u5982\u679c\u5de6\u8fb9\u7684\u503c\u672a\u786e\u5b9a\uff0c\u90a3\u4e48\u65e0\u6cd5\u4f7f\u7528\u6b64\u7d22\u5f15\u3002<\/p>\n<\/li>\n<\/ol>\n<h3><span class=\"ez-toc-section\" id=\"2_%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\"><\/span>2. \u547d\u540d\u89c4\u7ea6<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<h4><span class=\"ez-toc-section\" id=\"21_%E6%80%BB%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\"><\/span>2.1. \u603b\u547d\u540d\u89c4\u7ea6<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ol>\n<li>\n<p>\u4e0d\u5f97\u4f7f\u7528\u6570\u636e\u5e93\u4fdd\u7559\u5173\u952e\u5b57\uff0c\u4ee5\u53cajava\u7b49\u5e38\u7528\u8bed\u8a00\u7684\u4fdd\u7559\u5173\u952e\u5b57\uff0c\u6216\u8005\u53ef\u80fd\u6210\u4e3a\u5173\u952e\u5b57\u7684\u5355\u8bcd\u4f5c\u4e3a\u5b8c\u6574\u547d\u540d\u3002\uff08\u5bf9\u4e8e\u4e00\u4e9b\u7591\u4f3c\u5173\u952e\u5b57\u7684\u5355\u8bcd\uff0c\u53ef\u4ee5\u5728\u540e\u9762\u52a0\u4e00\u4e2a\u4e0b\u5212\u7ebf\u6765\u907f\u514d\uff0c\u4f8b\u5982 <code>key_<\/code>\uff09.<br \/>\n\u9644\uff1a<\/p>\n<ul>\n<li>MySQL\u4fdd\u7559\u5173\u952e\u5b57\u5217\u8868\uff1a<a target=\"_blank\" href=\"https:\/\/dev.mysql.com\/doc\/refman\/5.7\/en\/keywords.html\">https:\/\/dev.mysql.com\/doc\/refman\/5.7\/en\/keywords.html<\/a><\/li>\n<li>Java \u5173\u952e\u5b57\u5217\u8868\uff1a<a target=\"_blank\" href=\"https:\/\/www.w3schools.cn\/java\/java_ref_keywords.asp\">https:\/\/www.w3schools.cn\/java\/java_ref_keywords.asp<\/a><\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u8868\u540d\u3001\u5b57\u6bb5\u540d\u5fc5\u987b\u7528\u82f1\u6587\u5b57\u6bcd\u5f00\u5934\uff0c\u7981\u6b62\u51fa\u73b0\u6570\u5b57\u5f00\u5934\u3001\u91c7\u7528\u6709\u7279\u5f81\u542b\u4e49\u7684\u5355\u8bcd\u6216\u7f29\u5199\uff0c\u5355\u8bcd\u4e2d\u95f4\u7528 <code>_<\/code> \u5206\u5272\uff0c\u4e0d\u80fd\u7528\u53cc\u5f15\u53f7\u5305\u542b\u3002\u6570\u636e\u5e93\u5b57\u6bb5\u540d\u7684\u4fee\u6539\u4ee3\u4ef7\u5f88\u5927\uff0c\u56e0\u4e3a\u65e0\u6cd5\u8fdb\u884c\u9884\u53d1\u5e03\uff0c\u6240\u4ee5\u5b57\u6bb5\u540d\u79f0\u9700\u8981\u614e\u91cd\u8003\u8651\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>MySQL \u5728 Windows \u4e0b\u4e0d\u533a\u5206\u5927\u5c0f\u5199\uff0c\u4f46\u5728 Linux \u4e0b\u9ed8\u8ba4\u662f\u533a\u5206\u5927\u5c0f\u5199\u3002\u56e0\u6b64\uff0c\u6570\u636e\u5e93\u540d\u3001\u8868\u540d\u3001\u5b57\u6bb5\u540d\uff0c\u90fd\u4e0d\u5141\u8bb8\u51fa\u73b0\u4efb\u4f55\u5927\u5199\u5b57\u6bcd\uff0c\u907f\u514d\u8282\u5916\u751f\u679d\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span>aliyun_admin\uff0crdc_config\uff0clevel3_name<br \/>\n<span style='color:#ff7e66'><strong>\u53cd\u4f8b\uff1a<\/strong><\/span>AliyunAdmin\uff0crdcConfig\uff0clevel_3_name<\/p>\n<\/li>\n<li>\n<p>\u8868\u3001\u5b57\u6bb5\u3001\u7d22\u5f15\u7b49\u547d\u540d\u4e0d\u8d85\u8fc730\u4e2a\u5b57\u7b26\u3002\uff08<span style='color:red'>Oracle 11g\u4e2d\u5143\u6570\u636e\u7684\u540d\u79f0\u957f\u5ea6\u670930\u4e2a\u5b57\u7b26\u7684\u9650\u5236\uff0c\u5728Oracle12c\u53ca\u66f4\u9ad8\u7684\u7248\u672c\u4e2d\uff0c\u8fd9\u4e2a\u957f\u5ea6\u53ef\u8fbe\u5230128\u4e2a\u5b57\u7b26\uff0c\u800c\u5728MariaDB10.5\u7248\u672c\u4e2d\u8be5\u957f\u5ea6\u4e0d\u80fd\u8d85\u8fc764\u4e2a\u5b57\u7b26\u3002<\/span>\uff09<\/p>\n<\/li>\n<li>\n<p>\u5c0f\u6570\u7c7b\u578b\u4e3a decimal\uff0c\u7981\u6b62\u4f7f\u7528 float \u548c double\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u5728\u5b58\u50a8\u7684\u65f6\u5019\uff0c<code>float<\/code> \u548c <code>double<\/code> \u90fd\u5b58\u5728\u7cbe\u5ea6\u635f\u5931\u7684\u95ee\u9898\uff0c\u5f88\u53ef\u80fd\u5728\u6bd4\u8f83\u503c\u7684\u65f6\u5019\uff0c\u5f97\u5230\u4e0d\u6b63\u786e\u7684\u7ed3\u679c\u3002\u5982\u679c\u5b58\u50a8\u7684\u6570\u636e\u8303\u56f4\u8d85\u8fc7 <code>decimal<\/code> \u7684\u8303\u56f4\uff0c\u5efa\u8bae\u5c06\u6570\u636e\u62c6\u6210\u6574\u6570\u548c\u5c0f\u6570\u5e76\u5206\u5f00\u5b58\u50a8\u3002<\/p>\n<\/li>\n<li>\n<p>\u4e0d\u5f97\u4f7f\u7528\u5916\u952e\u4e0e\u7ea7\u8054\uff0c\u4e00\u5207\u5916\u952e\u6982\u5ff5\u5fc5\u987b\u5728\u5e94\u7528\u5c42\u89e3\u51b3\u3002\u5916\u952e\u4e0e\u7ea7\u8054\u66f4\u65b0\u9002\u7528\u4e8e\u5355\u673a\u4f4e\u5e76\u53d1\uff0c\u4e0d\u9002\u5408\u5206\u5e03\u5f0f\u3001\u9ad8\u5e76\u53d1\u96c6\u7fa4\uff1b\u7ea7\u8054\u66f4\u65b0\u662f\u5f3a\u963b\u585e\uff0c\u5b58\u5728\u6570\u636e\u5e93\u66f4\u65b0\u98ce\u66b4\u7684\u98ce\u9669\uff1b\u5916\u952e\u5f71\u54cd\u6570\u636e\u5e93\u7684\u63d2\u5165\u901f\u5ea6\u3002<\/p>\n<\/li>\n<\/ol>\n<h4><span class=\"ez-toc-section\" id=\"22_%E8%A1%A8%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\"><\/span>2.2. \u8868\u547d\u540d\u89c4\u7ea6<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ol>\n<li>\n<p>\u8868\u540d\u4e0d\u4f7f\u7528\u590d\u6570\u540d\u8bcd\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u8868\u540d\u5e94\u8be5\u4ec5\u4ec5\u8868\u793a\u8868\u91cc\u9762\u7684\u5b9e\u4f53\u5185\u5bb9\uff0c\u4e0d\u5e94\u8be5\u8868\u793a\u5b9e\u4f53\u6570\u91cf\uff0c\u5bf9\u5e94\u4e8e DO \u7c7b\u540d\u4e5f\u662f\u5355\u6570\u5f62\u5f0f\uff0c\u7b26\u5408\u8868\u8fbe\u4e60\u60ef\u3002<\/p>\n<\/li>\n<li>\n<p>\u8868\u5fc5\u5907\u4e09\u5b57\u6bb5\uff1aid, create_time, update_time\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u5176\u4e2d id \u5fc5\u4e3a\u4e3b\u952e\uff0c\u7c7b\u578b\u4e3a <code>bigint unsigned<\/code>\u3001\u5355\u8868\u65f6\u81ea\u589e\u3001\u6b65\u957f\u4e3a 1\u3002<code>create_time<\/code>, <code>update_time<\/code>\u7684\u7c7b\u578b\u5747\u4e3a <code>datetime<\/code> \u7c7b\u578b\uff0c\u524d\u8005\u73b0\u5728\u65f6\u8868\u793a\u4e3b\u52a8\u5f0f\u521b\u5efa\uff0c\u540e\u8005\u8fc7\u53bb\u5206\u8bcd\u8868\u793a\u88ab\u52a8\u5f0f\u66f4\u65b0\u3002<\/p>\n<\/li>\n<\/ol>\n<h4><span class=\"ez-toc-section\" id=\"23_%E5%AD%97%E6%AE%B5%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\"><\/span>2.3. \u5b57\u6bb5\u547d\u540d\u89c4\u7ea6<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ol>\n<li>\n<p>\u5404\u8868\u4e4b\u95f4\u76f8\u540c\u542b\u4e49\u7684\u5b57\u6bb5\uff0c\u7c7b\u578b\u5b9a\u4e49\u8981\u5b8c\u5168\u76f8\u540c\uff08\u5305\u62ec\u7cbe\u5ea6\u3001\u9ed8\u8ba4\u503c\u7b49\uff09\u3002<\/p>\n<\/li>\n<li>\n<p>\u5982\u679c\u5b58\u50a8\u7684\u5b57\u7b26\u4e32\u957f\u5ea6\u51e0\u4e4e\u76f8\u7b49\uff0c\u4f7f\u7528 char \u5b9a\u957f\u5b57\u7b26\u4e32\u7c7b\u578b\u3002<\/p>\n<\/li>\n<li>\n<p>varchar \u662f\u53ef\u53d8\u957f\u5b57\u7b26\u4e32\uff0c\u4e0d\u9884\u5148\u5206\u914d\u5b58\u50a8\u7a7a\u95f4\uff0c\u957f\u5ea6\u4e0d\u8981\u8d85\u8fc7 5000\uff0c\u5982\u679c\u5b58\u50a8\u957f\u5ea6\u5927\u4e8e\u6b64\u503c\uff0c\u5b9a\u4e49\u5b57\u6bb5\u7c7b\u578b\u4e3a text\uff0c\u72ec\u7acb\u51fa\u6765\u4e00\u5f20\u8868\uff0c\u7528\u4e3b\u952e\u6765\u5bf9\u5e94\uff0c\u907f\u514d\u5f71\u54cd\u5176\u5b83\u5b57\u6bb5\u7d22\u5f15\u6548\u7387\u3002<\/p>\n<\/li>\n<li>\n<p>\u8868\u8fbe\u662f\u4e0e\u5426\u6982\u5ff5\u7684\u5b57\u6bb5\uff0c\u5fc5\u987b\u4f7f\u7528 <code>is_xxx<\/code> \u7684\u65b9\u5f0f\u547d\u540d\uff0c\u6570\u636e\u7c7b\u578b\u662f <code>unsigned tinyint<\/code>\uff081 \u8868\u793a\u662f\uff0c0 \u8868\u793a\u5426\uff09\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u4efb\u4f55\u5b57\u6bb5\u5982\u679c\u4e3a\u975e\u8d1f\u6570\uff0c\u5fc5\u987b\u662f <code>unsigned<\/code>\u3002<br \/>\n<span style='color:#a06f02'><strong>\u6ce8\u610f\uff1a<\/strong><\/span>POJO \u7c7b\u4e2d\u7684\u4efb\u4f55\u5e03\u5c14\u7c7b\u578b\u7684\u53d8\u91cf\uff0c\u90fd\u4e0d\u8981\u52a0 <code>is<\/code> \u524d\u7f00\uff0c\u6240\u4ee5\uff0c\u9700\u8981\u5728 <code>&lt;resultMap&gt;<\/code> \u8bbe\u7f6e\u4ece <code>is_xxx<\/code> \u5230 <code>Xxx<\/code> \u7684\u6620\u5c04\u5173\u7cfb\u3002\u6570\u636e\u5e93\u8868\u793a\u662f\u4e0e\u5426\u7684\u503c\uff0c\u4f7f\u7528 <code>tinyint<\/code> \u7c7b\u578b\uff0c\u575a\u6301 <code>is_xxx<\/code> \u7684\u547d\u540d\u65b9\u5f0f\u662f\u4e3a\u4e86\u660e\u786e\u5176\u53d6\u503c\u542b\u4e49\u4e0e\u53d6\u503c\u8303\u56f4\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span>\u8868\u8fbe\u903b\u8f91\u5220\u9664\u7684\u5b57\u6bb5\u540d is_deleted\uff0c1-\u8868\u793a\u5220\u9664\uff0c0-\u8868\u793a\u672a\u5220\u9664\u3002<\/p>\n<\/li>\n<li>\n<p>\u5b57\u6bb5\u547d\u540d\u53ca\u5176\u6ce8\u91ca,\u8981\u505a\u5230\u6e05\u695a\u3001\u65e0\u6b67\u4e49\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u6709\u4e9b\u6570\u636e\u53ef\u80fd\u4f1a\u5b58\u5728\u591a\u79cd\u5b8c\u5168\u4e0d\u540c\u7c7b\u578b\u7684\u72b6\u6001\uff0c\u4f8b\u5982\uff1a\u4f8b\u5982\u6c7d\u8f66\u6570\u636e\u6709\u542f\u505c\u72b6\u6001\u3001\u53c2\u4fdd\u72b6\u6001\u3001\u7ef4\u4fee\u72b6\u6001\u3001\u5e74\u5ba1\u72b6\u6001\u2026\u2026\u603b\u4e4b\uff0c\u5728\u6709\u4e9b\u6570\u636e\u8868\u4e2d\uff0c\u6709\u8bb8\u591a\u7684\u72b6\u6001\u5b57\u6bb5\u3002\u4f8b\u5982\u6709\u4e2a\u5b57\u6bb5 <code>STATUS \u2013 \u72b6\u6001<\/code>\uff0c\u8fd9\u662f\u8ba9\u4eba\u5f88\u7591\u60d1\u7684\uff0c\u72b6\u6001\uff1f\u5230\u5e95\u662f\u4ec0\u4e48\u72b6\u6001\uff1f\u72b6\u6001\u7684\u53d6\u503c\u6709\u54ea\u4e9b\uff1f\u2014\u2014\u5982\u679c\u6539\u6210 <code>DELETE_STATUS \u2013 \u5220\u9664\u72b6\u6001(1-\u5df2\u5220\u9664,\u9ed8\u8ba4\u4e3a0-\u672a\u5220\u9664)<\/code>\uff0c\u8fd9\u6837\u7684\u547d\u540d\u548c\u6ce8\u91ca\uff0c\u8ba9\u4eba\u4e00\u76ee\u4e86\u7136\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u518d\u6bd4\u5982<code>belong_dept \u2013 \u6240\u5c5e\u90e8\u95e8<\/code>\uff0c\u8fd9\u4e5f\u6709\u6b67\u4e49\u3002\u56e0\u4e3a\u90e8\u95e8\u9664\u4e86\u6570\u636e\u552f\u4e00ID\u4e4b\u5916,\u8fd8\u6709\u4e00\u4e2a\u90e8\u95e8\u7f16\u7801CODE\u4e5f\u662f\u552f\u4e00\u7684\u3002\u90a3\u5230\u5e95\u662f\u5b58 \u90e8\u95e8ID\uff0c\u8fd8\u662f \u90e8\u95e8\u7f16\u7801 CODE\uff1f\u5b9e\u9645\u60c5\u51b5\u662f\uff0c\u6709\u7684\u4eba\u8ba4\u4e3a\u5b58ID\uff0c\u6709\u7684\u5374\u8ba4\u4e3a\u5b58\u7f16\u7801\u3002\u6240\u4ee5\uff0c\u5728\u547d\u540d\u4e0a\u5c31\u5e94\u8be5\u505a\u5230\u65e0\u6b67\u4e49,\u5982\u679c\u8981\u5b58ID\uff0c\u5c31\u5e94\u8be5\u547d\u540d\u4e3a<code>belong_dept_id \u2013 \u6240\u5c5e\u90e8\u95e8ID<\/code>\uff1b\u5982\u679c\u8981\u5b58\u90e8\u95e8\u7f16\u7801\uff0c\u5c31\u5e94\u8be5\u4e3a<code>belong_dept_code \u2013 \u6240\u5c5e\u90e8\u95e8\u7f16\u7801<\/code>\u3002<\/p>\n<\/li>\n<\/ol>\n<h4><span class=\"ez-toc-section\" id=\"24_%E7%BA%A6%E6%9D%9F%E4%B8%8E%E7%B4%A2%E5%BC%95%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\"><\/span>2.4. \u7ea6\u675f\u4e0e\u7d22\u5f15\u547d\u540d\u89c4\u7ea6<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ol>\n<li>\n<p>\u4e3b\u952e\u7ea6\u675f\u547d\u540d\uff1a<code>pk_\u8868\u540d<\/code><br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><code>pk_<\/code> \u5373 primary key \u7684\u7b80\u79f0\u3002<span style='color:red'>\u521b\u5efa\u4e3b\u952e\u7ea6\u675f\u65f6\uff0c\u4f1a\u81ea\u52a8\u7684\u521b\u5efa\u4e0e\u4e3b\u952e\u7ea6\u675f\u540c\u540d\u7684\u4e3b\u952e\u7d22\u5f15\u3002<\/span><\/p>\n<\/li>\n<li>\n<p>\u5916\u952e\u7ea6\u675f\u547d\u540d\uff1a<code>fk_\u8868\u540d_\u5b57\u6bb5\u540d<\/code><br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><code>fk_<\/code> \u5373 foreign key \u7684\u7b80\u79f0\u3002\u8868\u540d\u53ef\u4ee5\u53bb\u6389\u524d\u7f00\u3002<span style='color:red'>\u4e0d\u5efa\u8bae\u4f7f\u7528\u5916\u952e\u7ea6\u675f\uff0c\u4f46\u5728\u6570\u636e\u5e93\u6a21\u578b\u4e2d\u9700\u8981\u4f53\u73b0\u5916\u952e\u5173\u7cfb\u3002<\/span><\/p>\n<\/li>\n<li>\n<p>\u552f\u4e00\u7ea6\u675f\u547d\u540d\uff1a<code>uk_\u8868\u540d_\u5b57\u6bb5\u540d<\/code>\uff1b<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><code>uk_<\/code> \u5373 unique key \u7684\u7b80\u79f0\u3002\u8868\u540d\u53ef\u4ee5\u53bb\u6389\u524d\u7f00\u3002<span style='color:red'>\u521b\u5efa\u552f\u4e00\u7ea6\u675f\u65f6\uff0c\u4f1a\u81ea\u52a8\u7684\u521b\u5efa\u4e0e\u552f\u4e00\u7ea6\u675f\u540c\u540d\u7684\u552f\u4e00\u7d22\u5f15\u3002<\/span><\/p>\n<ul>\n<li>\u552f\u4e00\u7ea6\u675f\u548c\u552f\u4e00\u7d22\u5f15\uff0c\u90fd\u53ef\u4ee5\u5b9e\u73b0\u5217\u6570\u636e\u7684\u552f\u4e00\uff0c\u5217\u503c\u53ef\u4ee5\u6709null\u3002<\/li>\n<li>\u521b\u5efa\u552f\u4e00\u7ea6\u675f\uff0c\u4f1a\u81ea\u52a8\u521b\u5efa\u4e00\u4e2a\u540c\u540d\u7684\u552f\u4e00\u7d22\u5f15\uff0c\u8be5\u7d22\u5f15\u4e0d\u80fd\u5355\u72ec\u5220\u9664\uff0c\u5220\u9664\u7ea6\u675f\u4f1a\u81ea\u52a8\u5220\u9664\u7d22\u5f15\u3002\u552f\u4e00\u7ea6\u675f\u662f\u901a\u8fc7\u552f\u4e00\u7d22\u5f15\u6765\u5b9e\u73b0\u6570\u636e\u7684\u552f\u4e00\u3002<\/li>\n<li>\u521b\u5efa\u4e00\u4e2a\u552f\u4e00\u7d22\u5f15\uff0c\u8fd9\u4e2a\u7d22\u5f15\u5c31\u662f\u72ec\u7acb\uff0c\u53ef\u4ee5\u5355\u72ec\u5220\u9664\u3002<\/li>\n<li>\u5982\u679c\u4e00\u4e2a\u5217\u4e0a\u60f3\u6709\u7ea6\u675f\u548c\u7d22\u5f15\uff0c\u4e14\u4e24\u8005\u53ef\u4ee5\u5355\u72ec\u7684\u5220\u9664\u3002\u53ef\u4ee5\u5148\u5efa\u552f\u4e00\u7d22\u5f15\uff0c\u518d\u5efa\u540c\u540d\u7684\u552f\u4e00\u7ea6\u675f\u3002<\/li>\n<li>\u5982\u679c\u8868\u7684\u4e00\u4e2a\u5b57\u6bb5\uff0c\u8981\u4f5c\u4e3a\u53e6\u5916\u4e00\u4e2a\u8868\u7684\u5916\u952e\uff0c\u8fd9\u4e2a\u5b57\u6bb5\u5fc5\u987b\u6709\u552f\u4e00\u7ea6\u675f\uff08\u6216\u662f\u4e3b\u952e\uff09\uff0c\u5982\u679c\u53ea\u662f\u6709\u552f\u4e00\u7d22\u5f15\uff0c\u5c31\u4f1a\u62a5\u9519\u3002<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u666e\u901a\u7d22\u5f15\u547d\u540d\uff1a <code>idx_\u8868\u540d_\u5b57\u6bb5\u540d<\/code>\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><code>idx_<\/code> \u5373 index \u7684\u7b80\u79f0\u3002\u8868\u540d\u53ef\u4ee5\u53bb\u6389\u524d\u7f00\u3002\u5982\u679c\u590d\u5408\u7d22\u5f15\u7684\u6784\u6210\u5b57\u6bb5\u8f83\u591a\uff0c\u5219\u53ea\u5305\u542b\u7b2c\u4e00\u4e2a\u5b57\u6bb5\uff0c\u5e76\u6dfb\u52a0\u5e8f\u53f7\u3002<\/p>\n<\/li>\n<\/ol>\n<h4><span class=\"ez-toc-section\" id=\"25_%E5%85%B6%E4%BB%96%E5%91%BD%E5%90%8D%E8%A7%84%E7%BA%A6\"><\/span>2.5. \u5176\u4ed6\u547d\u540d\u89c4\u7ea6<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ol>\n<li>\n<p>\u51fd\u6570\u547d\u540d\uff1a<code>fn_\u6a21\u5757\u540d\u79f0_\u529f\u80fd\u63cf\u8ff0<\/code>\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span> <code>fn_<\/code> \u5373 function \u7684\u7b80\u79f0\u3002\u51fd\u6570\u540d\u5e94\u4e0e\u5176\u5b9e\u9645\u529f\u80fd\u4fdd\u6301\u4e00\u81f4\uff0c\u5bfc\u81f4\u53d1\u751f\u67d0\u52a8\u4f5c\u5e94\u4ee5\u52a8\u8bcd\u4e3a\u524d\u7f00\u547d\u540d\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span><code>fn_public_getdate<\/code>\uff08\u516c\u5171\u51fd\u6570\uff1a\u83b7\u53d6\u65e5\u671f\uff09<\/p>\n<\/li>\n<li>\n<p>\u5b58\u50a8\u8fc7\u7a0b\u547d\u540d\uff1a<code>sp_\u6a21\u5757\u540d\u79f0_\u529f\u80fd\u63cf\u8ff0<\/code><br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><code>sp_<\/code> \u5373 storage procedure \u7684\u7b80\u79f0\u3002\u547d\u540d\u65b9\u5f0f\u540c\u51fd\u6570\u547d\u540d\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span><code>sp_admin_getparameters<\/code>(\u7ba1\u7406\u6a21\u5757\u7684\u5b58\u50a8\u8fc7\u7a0b\uff1a\u83b7\u53d6\u53c2\u6570)\u3002<\/p>\n<\/li>\n<li>\n<p>\u89c6\u56fe\u547d\u540d\uff1a<code>vw_\u6a21\u5757\u540d\u79f0_\u529f\u80fd\u63cf\u8ff0<\/code><br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><code>vw_<\/code> \u662f view \u7684\u7b80\u79f0\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span><code>vw_user_detail<\/code>(\u7528\u6237\u8be6\u60c5\u89c6\u56fe)<\/p>\n<\/li>\n<li>\n<p>\u5305\u547d\u540d\uff1a<code>pkg_\u6a21\u5757\u540d\u79f0_\u529f\u80fd\u63cf\u8ff0<\/code><br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><code>pkg_<\/code> \u662f package \u7684\u7b80\u79f0\u3002<\/p>\n<\/li>\n<li>\n<p>\u5e8f\u5217\u547d\u540d\uff1a<code>seq_\u8868\u540d_\u5b57\u6bb5\u540d<\/code><br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><code>seq_<\/code> \u662f sequence \u7684\u7b80\u79f0\u3002\u5982\u679c\u53ea\u6709\u4e3b\u952e\u7528\u5230\u5e8f\u5217\uff0c\u5219\u53ef\u7b80\u5199\u4e3a\uff1a<code>seq_\u8868\u540d<\/code>\u3002<\/p>\n<\/li>\n<li>\n<p>\u89e6\u53d1\u5668\u547d\u540d\uff1a<code>tr_\u8868\u540d_\u5b57\u6bb5\u540d<\/code><br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><code>tr_<\/code> \u662f trigger \u7684\u7b80\u79f0\u3002<\/p>\n<\/li>\n<\/ol>\n<h3><span class=\"ez-toc-section\" id=\"3_SQL%E8%A7%84%E7%BA%A6\"><\/span>3. SQL\u89c4\u7ea6<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ol>\n<li>\n<p>\u4e0d\u8981\u4f7f\u7528 count(\u5217\u540d)\u6216 count(\u5e38\u91cf)\u6765\u66ff\u4ee3 <code>count(*)<\/code>\uff0c<code>count(*)<\/code>\u662f SQL92 \u5b9a\u4e49\u7684\u6807\u51c6\u7edf\u8ba1\u884c\u6570\u7684\u8bed\u6cd5\uff0c\u8ddf\u6570\u636e\u5e93\u65e0\u5173\uff0c\u8ddf NULL \u548c\u975e NULL \u65e0\u5173\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><code>count(*)<\/code>\u4f1a\u7edf\u8ba1\u503c\u4e3a NULL \u7684\u884c\uff0c\u800ccount(\u5217\u540d)\u4e0d\u4f1a\u7edf\u8ba1\u6b64\u5217\u4e3a NULL \u503c\u7684\u884c\u3002<\/p>\n<\/li>\n<li>\n<p>count(distinct col) \u8ba1\u7b97\u8be5\u5217\u9664 NULL \u4e4b\u5916\u7684\u4e0d\u91cd\u590d\u884c\u6570\uff0c\u6ce8\u610f count(distinct col1, col2) \u5982\u679c\u5176\u4e2d\u4e00\u5217\u5168\u4e3a NULL\uff0c\u90a3\u4e48\u5373\u4f7f\u53e6\u4e00\u5217\u6709\u4e0d\u540c\u7684\u503c\uff0c\u4e5f\u8fd4\u56de\u4e3a 0\u3002<\/p>\n<\/li>\n<li>\n<p>\u5f53\u67d0\u4e00\u5217\u7684\u503c\u5168\u662f NULL \u65f6\uff0ccount(col)\u7684\u8fd4\u56de\u7ed3\u679c\u4e3a 0\uff0c\u4f46 sum(col)\u7684\u8fd4\u56de\u7ed3\u679c\u4e3aNULL\uff0c\u56e0\u6b64\u4f7f\u7528 sum()\u65f6\u9700\u6ce8\u610f NPE \u95ee\u9898\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span>\u53ef\u4ee5\u4f7f\u7528\u5982\u4e0b\u65b9\u5f0f\u6765\u907f\u514d sum \u7684 NPE \u95ee\u9898\uff1a<code>SELECT IFNULL(SUM(column), 0) FROM table;<\/code><\/p>\n<\/li>\n<li>\n<p>\u4f7f\u7528 ISNULL()\u6765\u5224\u65ad\u662f\u5426\u4e3a NULL \u503c\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>NULL \u4e0e\u4efb\u4f55\u503c\u7684\u76f4\u63a5\u6bd4\u8f83\u90fd\u4e3a NULL\u3002<br \/>\n1\uff09 <code>NULL&lt;&gt;NULL<\/code> \u7684\u8fd4\u56de\u7ed3\u679c\u662f NULL\uff0c\u800c\u4e0d\u662f false\u3002<br \/>\n2\uff09 <code>NULL=NULL<\/code> \u7684\u8fd4\u56de\u7ed3\u679c\u662f NULL\uff0c\u800c\u4e0d\u662f true\u3002<br \/>\n3\uff09 <code>NULL&lt;&gt;1<\/code> \u7684\u8fd4\u56de\u7ed3\u679c\u662f NULL\uff0c\u800c\u4e0d\u662f true\u3002<br \/>\n<span style='color:#ff7e66'><strong>\u53cd\u4f8b\uff1a<\/strong><\/span>\u5728 SQL \u8bed\u53e5\u4e2d\uff0c\u5982\u679c\u5728 null \u524d\u6362\u884c\uff0c\u5f71\u54cd\u53ef\u8bfb\u6027\u3002<code>select * from table where column1 is null and column3 is not null;<\/code> \u800c<code>ISNULL(column)<\/code>\u662f\u4e00\u4e2a\u6574\u4f53\uff0c\u7b80\u6d01\u6613\u61c2\u3002\u4ece\u6027\u80fd\u6570\u636e\u4e0a\u5206\u6790\uff0c<code>ISNULL(column)<\/code><br \/>\n\u6267\u884c\u6548\u7387\u66f4\u5feb\u4e00\u4e9b\u3002<\/p>\n<\/li>\n<li>\n<p>\u4ee3\u7801\u4e2d\u5199\u5206\u9875\u67e5\u8be2\u903b\u8f91\u65f6\uff0c\u82e5 count \u4e3a 0 \u5e94\u76f4\u63a5\u8fd4\u56de\uff0c\u907f\u514d\u6267\u884c\u540e\u9762\u7684\u5206\u9875\u8bed\u53e5\u3002<\/p>\n<\/li>\n<li>\n<p>\u4e0d\u5f97\u4f7f\u7528\u5916\u952e\u4e0e\u7ea7\u8054\uff0c\u4e00\u5207\u5916\u952e\u6982\u5ff5\u5fc5\u987b\u5728\u5e94\u7528\u5c42\u89e3\u51b3\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\uff08\u6982\u5ff5\u89e3\u91ca\uff09\u5b66\u751f\u8868\u4e2d\u7684 student_id \u662f\u4e3b\u952e\uff0c\u90a3\u4e48\u6210\u7ee9\u8868\u4e2d\u7684 student_id \u5219\u4e3a\u5916\u952e\u3002\u5982\u679c\u66f4\u65b0\u5b66\u751f\u8868\u4e2d\u7684 student_id\uff0c\u540c\u65f6\u89e6\u53d1\u6210\u7ee9\u8868\u4e2d\u7684 student_id \u66f4\u65b0\uff0c\u5373\u4e3a\u7ea7\u8054\u66f4\u65b0\u3002\u5916\u952e\u4e0e\u7ea7\u8054\u66f4\u65b0\u9002\u7528\u4e8e\u5355\u673a\u4f4e\u5e76\u53d1\uff0c\u4e0d\u9002\u5408\u5206\u5e03\u5f0f\u3001\u9ad8\u5e76\u53d1\u96c6\u7fa4\uff1b\u7ea7\u8054\u66f4\u65b0\u662f\u5f3a\u963b\u585e\uff0c\u5b58\u5728\u6570\u636e\u5e93\u66f4\u65b0\u98ce\u66b4\u7684\u98ce\u9669\uff1b\u5916\u952e\u5f71\u54cd\u6570\u636e\u5e93\u7684\u63d2\u5165\u901f\u5ea6\u3002<\/p>\n<\/li>\n<li>\n<p>\u7981\u6b62\u4f7f\u7528\u5b58\u50a8\u8fc7\u7a0b\uff0c\u5b58\u50a8\u8fc7\u7a0b\u96be\u4ee5\u8c03\u8bd5\u548c\u6269\u5c55\uff0c\u66f4\u6ca1\u6709\u79fb\u690d\u6027\u3002<\/p>\n<\/li>\n<li>\n<p>\u6570\u636e\u8ba2\u6b63\uff08\u7279\u522b\u662f\u5220\u9664\u6216\u4fee\u6539\u8bb0\u5f55\u64cd\u4f5c\uff09\u65f6\uff0c\u8981\u5148 select\uff0c\u907f\u514d\u51fa\u73b0\u8bef\u5220\u9664\uff0c\u786e\u8ba4\u65e0\u8bef\u624d\u80fd\u6267\u884c\u66f4\u65b0\u8bed\u53e5\u3002<\/p>\n<\/li>\n<li>\n<p>\u5bf9\u4e8e\u6570\u636e\u5e93\u4e2d\u8868\u8bb0\u5f55\u7684\u67e5\u8be2\u548c\u53d8\u66f4\uff0c\u53ea\u8981\u6d89\u53ca\u591a\u4e2a\u8868\uff0c\u90fd\u9700\u8981\u5728\u5217\u540d\u524d\u52a0\u8868\u7684\u522b\u540d\uff08\u6216\u8868\u540d\uff09\u8fdb\u884c\u9650\u5b9a\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span>\u5bf9\u591a\u8868\u8fdb\u884c\u67e5\u8be2\u8bb0\u5f55\u3001\u66f4\u65b0\u8bb0\u5f55\u3001\u5220\u9664\u8bb0\u5f55\u65f6\uff0c\u5982\u679c\u5bf9\u64cd\u4f5c\u5217\u6ca1\u6709\u9650\u5b9a\u8868\u7684\u522b\u540d\uff08\u6216\u8868\u540d\uff09\uff0c\u5e76\u4e14\u64cd\u4f5c\u5217\u5728\u591a\u4e2a\u8868\u4e2d\u5b58\u5728\u65f6\uff0c\u5c31\u4f1a\u629b\u5f02\u5e38\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span><code>select t1.name from table_first as t1 , table_second as t2 where t1.id=t2.id;<\/code><br \/>\n<span style='color:#ff7e66'><strong>\u53cd\u4f8b\uff1a<\/strong><\/span>\u5728\u67d0\u4e1a\u52a1\u4e2d\uff0c\u7531\u4e8e\u591a\u8868\u5173\u8054\u67e5\u8be2\u8bed\u53e5\u6ca1\u6709\u52a0\u8868\u7684\u522b\u540d\uff08\u6216\u8868\u540d\uff09\u7684\u9650\u5236\uff0c\u6b63\u5e38\u8fd0\u884c\u4e24\u5e74\u540e\uff0c\u6700\u8fd1\u5728\u67d0\u4e2a\u8868\u4e2d\u589e\u52a0\u4e00\u4e2a\u540c\u540d\u5b57\u6bb5\uff0c\u5728\u9884\u53d1\u5e03\u73af\u5883\u505a\u6570\u636e\u5e93\u53d8\u66f4\u540e\uff0c\u7ebf\u4e0a\u67e5\u8be2\u8bed\u53e5\u51fa\u73b0\u51fa 1052 \u5f02\u5e38\uff1a<code>Column &#039;name&#039; in field list is ambiguous\u3002<\/code><\/p>\n<\/li>\n<li>\n<p>SQL \u8bed\u53e5\u4e2d\u8868\u7684\u522b\u540d\u524d\u52a0 AS\uff0c\u5e76\u4e14\u4ee5 t1\u3001t2\u3001t3\u3001...\u7684\u987a\u5e8f\u4f9d\u6b21\u547d\u540d\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><br \/>\n1\uff09\u522b\u540d\u53ef\u4ee5\u662f\u8868\u7684\u7b80\u79f0\uff0c\u6216\u8005\u662f\u4f9d\u7167\u8868\u5728 SQL \u8bed\u53e5\u4e2d\u51fa\u73b0\u7684\u987a\u5e8f\uff0c\u4ee5 t1\u3001t2\u3001t3 \u7684\u65b9\u5f0f\u547d\u540d\u3002<br \/>\n2\uff09\u522b\u540d\u524d\u52a0 AS \u4f7f\u522b\u540d\u66f4\u5bb9\u6613\u8bc6\u522b\u3002<br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span><code>select t1.name from table_first as t1, table_second as t2 where t1.id=t2.id;<\/code><\/p>\n<\/li>\n<li>\n<p>in \u64cd\u4f5c\u80fd\u907f\u514d\u5219\u907f\u514d\uff0c\u82e5\u5b9e\u5728\u907f\u514d\u4e0d\u4e86\uff0c\u9700\u8981\u4ed4\u7ec6\u8bc4\u4f30 in \u540e\u8fb9\u7684\u96c6\u5408\u5143\u7d20\u6570\u91cf\uff0c\u63a7\u5236\u5728 1000 \u4e2a\u4e4b\u5185\u3002<\/p>\n<\/li>\n<li>\n<p>\u56e0\u56fd\u9645\u5316\u9700\u8981\uff0c\u6240\u6709\u7684\u5b57\u7b26\u5b58\u50a8\u4e0e\u8868\u793a\uff0c\u5747\u91c7\u7528 utf8 \u5b57\u7b26\u96c6\uff0c\u90a3\u4e48\u5b57\u7b26\u8ba1\u6570\u65b9\u6cd5\u9700\u8981\u6ce8\u610f\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><br \/>\n<code>SELECT LENGTH(&quot;\u8f7b\u677e\u5de5\u4f5c&quot;)\uff1b<\/code> \u8fd4\u56de\u4e3a 12<br \/>\n<code>SELECT CHARACTER_LENGTH(&quot;\u8f7b\u677e\u5de5\u4f5c&quot;)\uff1b<\/code> \u8fd4\u56de\u4e3a 4<br \/>\n\u5982\u679c\u9700\u8981\u5b58\u50a8\u8868\u60c5\uff0c\u90a3\u4e48\u9009\u62e9 utf8mb4 \u6765\u8fdb\u884c\u5b58\u50a8\uff0c\u6ce8\u610f\u5b83\u4e0e utf8 \u7f16\u7801\u7684\u533a\u522b\u3002<\/p>\n<\/li>\n<li>\n<p>TRUNCATE TABLE \u6bd4 DELETE \u901f\u5ea6\u5feb\uff0c\u4e14\u4f7f\u7528\u7684\u7cfb\u7edf\u548c\u4e8b\u52a1\u65e5\u5fd7\u8d44\u6e90\u5c11\uff0c\u4f46 TRUNCATE \u65e0\u4e8b\u52a1\u4e14\u4e0d\u89e6\u53d1 trigger\uff0c\u6709\u53ef\u80fd\u9020\u6210\u4e8b\u6545\uff0c\u6545\u4e0d\u5efa\u8bae\u5728\u5f00\u53d1\u4ee3\u7801\u4e2d\u4f7f\u7528\u6b64\u8bed\u53e5\u3002<br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><code>TRUNCATE TABLE<\/code> \u5728\u529f\u80fd\u4e0a\u4e0e\u4e0d\u5e26 WHERE \u5b50\u53e5\u7684 DELETE \u8bed\u53e5\u76f8\u540c\u3002<\/p>\n<\/li>\n<\/ol>\n<h3><span class=\"ez-toc-section\" id=\"%E9%99%84%E5%BD%95\"><\/span>\u9644\u5f55<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<h4><span class=\"ez-toc-section\" id=\"%E9%99%84%E5%BD%95A_%E7%9B%B8%E5%85%B3%E8%81%94%E7%9A%84%E6%96%87%E7%AB%A0\"><\/span>\u9644\u5f55A. \u76f8\u5173\u8054\u7684\u6587\u7ae0<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p><span style='color:#c5376c'><strong>\u3010\u5f3a\u5236\u3011<\/strong><\/span><br \/>\n<span style='color:#a06f02'><strong>\u8bf4\u660e\uff1a<\/strong><\/span><br \/>\n<span style='color:#5ba87f'><strong>\u6b63\u4f8b\uff1a<\/strong><\/span><br \/>\n<span style='color:#ff7e66'><strong>\u53cd\u4f8b\uff1a<\/strong><\/span><br \/>\n<span style='color:#ffd468'><strong>\u3010\u63a8\u8350\u3011<\/strong><\/span><br \/>\n<span style='color:#8fb18c'><strong>\u3010\u53c2\u8003\u3011<\/strong><\/span><\/p>\n<h4><span class=\"ez-toc-section\" id=\"%E9%99%84%E5%BD%95B_%E5%85%B6%E4%BB%96%E5%8F%82%E8%80%83\"><\/span>\u9644\u5f55B. \u5176\u4ed6\u53c2\u8003<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li>\n<p><a target=\"_blank\" href=\"https:\/\/blog.csdn.net\/qq_35385687\/article\/details\/113979420\" title=\"\u6570\u636e\u5e93\u8bbe\u8ba1\u6587\u6863\u89c4\u8303\">\u6570\u636e\u5e93\u8bbe\u8ba1\u6587\u6863\u89c4\u8303<\/a><\/p>\n<\/li>\n<li>\n<p><a target=\"_blank\" href=\"https:\/\/xie.infoq.cn\/article\/c48b73ed84652f5b3d865c819\" title=\"MySQL \u7d22\u5f15 15 \u8fde\u95ee\uff0c\u4f60\u625b\u5f97\u4f4f\u5417\uff1f\">MySQL \u7d22\u5f15 15 \u8fde\u95ee\uff0c\u4f60\u625b\u5f97\u4f4f\u5417\uff1f<\/a><\/p>\n<\/li>\n<\/ul>\n<h4><span class=\"ez-toc-section\" id=\"%E9%99%84%E5%BD%95C_%E6%95%B0%E6%8D%AE%E5%BA%93%E8%AE%BE%E8%AE%A1%E4%B8%89%E8%8C%83%E5%BC%8F\"><\/span>\u9644\u5f55C. \u6570\u636e\u5e93\u8bbe\u8ba1\u4e09\u8303\u5f0f<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li>\n<p>\u4ec0\u4e48\u662f\u8303\u5f0f<br \/>\n\u89c4\u8303\u7684\u6570\u636e\u5e93\u5c31\u9700\u8981\u6ee1\u8db3\u4e00\u4e9b\u89c4\u5219\u6765\u4f18\u5316\u6570\u636e\u7684\u8bbe\u8ba1\u548c\u5b58\u50a8\uff0c\u8fd9\u4e9b\u89c4\u5219\u5c31\u79f0\u4e3a\u8303\u5f0f\u3002<\/p>\n<\/li>\n<li>\n<p>\u4e09\u5927\u8303\u5f0f<br \/>\n\u76ee\u524d\u5173\u7cfb\u6570\u636e\u5e93\u6709\u516d\u79cd\u8303\u5f0f\uff1a\u7b2c\u4e00\u8303\u5f0f\uff081NF\uff09\u3001\u7b2c\u4e8c\u8303\u5f0f\uff082NF\uff09\u3001\u7b2c\u4e09\u8303\u5f0f\uff083NF\uff09\u3001\u5df4\u65af-\u79d1\u5fb7\u8303\u5f0f\uff08BCNF\uff09\u3001\u7b2c\u56db\u8303\u5f0f(4NF\uff09\u548c\u7b2c\u4e94\u8303\u5f0f\uff085NF\uff0c\u53c8\u79f0\u5b8c\u7f8e\u8303\u5f0f\uff09\u3002<br \/>\n\u6ee1\u8db3\u6700\u4f4e\u8981\u6c42\u7684\u8303\u5f0f\u662f\u7b2c\u4e00\u8303\u5f0f\uff081NF\uff09\u3002\u5728\u7b2c\u4e00\u8303\u5f0f\u7684\u57fa\u7840\u4e0a\u8fdb\u4e00\u6b65\u6ee1\u8db3\u66f4\u591a\u89c4\u8303\u8981\u6c42\u7684\u79f0\u4e3a\u7b2c\u4e8c\u8303\u5f0f\uff082NF\uff09\uff0c\u5176\u4f59\u8303\u5f0f\u4ee5\u6b21\u7c7b\u63a8\u3002\u4e00\u822c\u8bf4\u6765\uff0c\u6570\u636e\u5e93\u53ea\u9700\u6ee1\u8db3\u7b2c\u4e09\u8303\u5f0f(3NF\uff09\u5c31\u884c\u4e86\u3002<\/p>\n<\/li>\n<li>\n<p>\u7b2c\u4e00\u8303\u5f0f1NF<br \/>\n\u6570\u636e\u5e93\u8868\u7684\u6bcf\u4e00\u5217\u90fd\u662f\u4e0d\u53ef\u5206\u5272\u7684\u539f\u5b50\u6570\u636e\u9879\uff0c\u4e0d\u80fd\u662f\u96c6\u5408\u3001\u6570\u7ec4\u7b49\u975e\u539f\u5b50\u6570\u636e\u9879\u3002\u5373\u8868\u4e2d\u7684\u67d0\u4e2a\u5217\u6709\u591a\u4e2a\u503c\u65f6\uff0c\u5fc5\u987b\u62c6\u5206\u4e3a\u4e0d\u540c\u7684\u5217\u3002\u7b80\u800c\u8a00\u4e4b\uff0c\u7b2c\u4e00\u8303\u5f0f\u6bcf\u4e00\u5217\u4e0d\u53ef\u518d\u62c6\u5206\uff0c\u79f0\u4e3a\u539f\u5b50\u6027\u3002<br \/>\n<a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/12\/image-1672209035520.png\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/12\/image-1672209035520.png\" alt=\"file\" \/><\/a><\/p>\n<\/li>\n<li>\n<p>\u7b2c\u4e8c\u8303\u5f0f2NF<br \/>\n\u5728\u6ee1\u8db3\u7b2c\u4e00\u8303\u5f0f\u7684\u524d\u63d0\u4e0b\uff0c\u8868\u4e2d\u7684\u6bcf\u4e00\u4e2a\u5b57\u6bb5\u90fd\u5b8c\u5168\u4f9d\u8d56\u4e8e\u4e3b\u952e\u3002<br \/>\n\u6240\u8c13\u5b8c\u5168\u4f9d\u8d56\u662f\u6307\u4e0d\u80fd\u5b58\u5728\u4ec5\u4f9d\u8d56\u4e3b\u952e\u4e00\u90e8\u5206\u7684\u5217\u3002\u7b80\u800c\u8a00\u4e4b\uff0c\u7b2c\u4e8c\u8303\u5f0f\u5c31\u662f\u5728\u7b2c\u4e00\u8303\u5f0f\u7684\u57fa\u7840\u4e0a\u6240\u6709\u5217\u5b8c\u5168\u4f9d\u8d56\u4e8e\u4e3b\u952e\u5217\u3002\u5f53\u5b58\u5728\u4e00\u4e2a\u590d\u5408\u4e3b\u952e\u5305\u542b\u591a\u4e2a\u4e3b\u952e\u5217\u7684\u65f6\u5019\uff0c\u624d\u4f1a\u53d1\u751f\u4e0d\u7b26\u5408\u7b2c\u4e8c\u8303\u5f0f\u7684\u60c5\u51b5\u3002(\u6bd4\u5982\u6709\u4e00\u4e2a\u4e3b\u952e\u6709\u4e24\u4e2a\u5217\uff0c\u4e0d\u80fd\u5b58\u5728\u8fd9\u6837\u7684\u5c5e\u6027\uff0c\u5b83\u53ea\u4f9d\u8d56\u4e8e\u5176\u4e2d\u4e00\u4e2a\u5217\uff0c\u8fd9\u5c31\u662f\u4e0d\u7b26\u5408\u7b2c\u4e8c\u8303\u5f0f\u3002)<\/p>\n<ul>\n<li>\u7279\u70b9\uff1a\n<ol>\n<li>\u4e00\u5f20\u8868\u53ea\u63cf\u8ff0\u4e00\u4ef6\u4e8b\u60c5\u3002<\/li>\n<li>\u8868\u4e2d\u7684\u6bcf\u4e00\u5217\u90fd\u5b8c\u5168\u4f9d\u8d56\u4e8e\u4e3b\u952e\u3002<\/li>\n<\/ol>\n<\/li>\n<li>\u6982\u5ff5\uff1a\n<ol>\n<li>\u51fd\u6570\u4f9d\u8d56\uff1aA\u2013&gt;B,\u5982\u679c\u901a\u8fc7A\u5c5e\u6027(\u5c5e\u6027\u7ec4)\u7684\u503c\uff0c\u53ef\u4ee5\u786e\u5b9a\u552f\u4e00B\u5c5e\u6027\u7684\u503c\u3002\u5219\u79f0B\u4f9d\u8d56\u4e8eA<br \/>\n\u4f8b\u5982\uff1a\u5b66\u53f7\u2013&gt;\u59d3\u540d\u3002 \uff08\u5b66\u53f7\uff0c\u8bfe\u7a0b\u540d\u79f0\uff09 --&gt; \u5206\u6570<\/li>\n<li>\u5b8c\u5168\u51fd\u6570\u4f9d\u8d56\uff1aA\u2013&gt;B\uff0c \u5982\u679cA\u662f\u4e00\u4e2a\u5c5e\u6027\u7ec4\uff0c\u5219B\u5c5e\u6027\u503c\u5f97\u786e\u5b9a\u9700\u8981\u4f9d\u8d56\u4e8eA\u5c5e\u6027\u7ec4\u4e2d\u6240\u6709\u7684\u5c5e\u6027\u503c\u3002<br \/>\n\u4f8b\u5982\uff1a\uff08\u5b66\u53f7\uff0c\u8bfe\u7a0b\u540d\u79f0\uff09 --&gt; \u5206\u6570<\/li>\n<li>\u90e8\u5206\u51fd\u6570\u4f9d\u8d56\uff1aA\u2013&gt;B\uff0c \u5982\u679cA\u662f\u4e00\u4e2a\u5c5e\u6027\u7ec4\uff0c\u5219B\u5c5e\u6027\u503c\u5f97\u786e\u5b9a\u53ea\u9700\u8981\u4f9d\u8d56\u4e8eA\u5c5e\u6027\u7ec4\u4e2d\u67d0\u4e00\u4e9b\u503c\u5373\u53ef\u3002<br \/>\n\u4f8b\u5982\uff1a\uff08\u5b66\u53f7\uff0c\u8bfe\u7a0b\u540d\u79f0\uff09 \u2013 &gt; \u59d3\u540d<\/li>\n<li>\u4f20\u9012\u51fd\u6570\u4f9d\u8d56\uff1aA\u2013&gt;B, B \u2013 &gt;C . \u5982\u679c\u901a\u8fc7A\u5c5e\u6027(\u5c5e\u6027\u7ec4)\u7684\u503c\uff0c\u53ef\u4ee5\u786e\u5b9a\u552f\u4e00B\u5c5e\u6027\u7684\u503c\uff0c\u5728\u901a\u8fc7B\u5c5e\u6027\uff08\u5c5e\u6027\u7ec4\uff09\u7684\u503c\u53ef\u4ee5\u786e\u5b9a\u552f\u4e00C\u5c5e\u6027\u7684\u503c\uff0c\u5219\u79f0 C \u4f20\u9012\u51fd\u6570\u4f9d\u8d56\u4e8eA<br \/>\n\u4f8b\u5982\uff1a\u5b66\u53f7\u2013&gt;\u7cfb\u540d\uff0c\u7cfb\u540d\u2013&gt;\u7cfb\u4e3b\u4efb<\/li>\n<li>\u7801\uff1a\u5982\u679c\u5728\u4e00\u5f20\u8868\u4e2d\uff0c\u4e00\u4e2a\u5c5e\u6027\u6216\u5c5e\u6027\u7ec4\uff0c\u88ab\u5176\u4ed6\u6240\u6709\u5c5e\u6027\u6240\u5b8c\u5168\u4f9d\u8d56\uff0c\u5219\u79f0\u8fd9\u4e2a\u5c5e\u6027(\u5c5e\u6027\u7ec4)\u4e3a\u8be5\u8868\u7684\u7801<br \/>\n\u4f8b\u5982\uff1a\u8be5\u8868\u4e2d\u7801\u4e3a\uff1a\uff08\u5b66\u53f7\uff0c\u8bfe\u7a0b\u540d\u79f0\uff09<br \/>\n\u4e3b\u5c5e\u6027\uff1a\u7801\u5c5e\u6027\u7ec4\u4e2d\u7684\u6240\u6709\u5c5e\u6027<br \/>\n\u975e\u4e3b\u5c5e\u6027\uff1a\u9664\u8fc7\u7801\u5c5e\u6027\u7ec4\u7684\u5c5e\u6027<br \/>\n<a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/12\/image-1672209075097.png\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/12\/image-1672209075097.png\" alt=\"file\" \/><\/a><\/li>\n<\/ol>\n<\/li>\n<\/ul>\n<\/li>\n<li>\n<p>\u7b2c\u4e09\u8303\u5f0f3NF<br \/>\n\u5728\u6ee1\u8db3\u7b2c\u4e8c\u8303\u5f0f\u7684\u524d\u63d0\u4e0b\uff0c\u8868\u4e2d\u7684\u6bcf\u4e00\u5217\u90fd\u76f4\u63a5\u4f9d\u8d56\u4e8e\u4e3b\u952e\uff0c\u800c\u4e0d\u662f\u901a\u8fc7\u5176\u5b83\u7684\u5217\u6765\u95f4\u63a5\u4f9d\u8d56\u4e8e\u4e3b\u952e\u3002<br \/>\n\u7b80\u800c\u8a00\u4e4b\uff0c\u7b2c\u4e09\u8303\u5f0f\u5c31\u662f\u6240\u6709\u5217\u4e0d\u4f9d\u8d56\u4e8e\u5176\u5b83\u975e\u4e3b\u952e\u5217\uff0c\u4e5f\u5c31\u662f\u5728\u6ee1\u8db3 2NF \u7684\u57fa\u7840\u4e0a\uff0c\u4efb\u4f55\u975e\u4e3b\u5217\u4e0d\u5f97\u4f20\u9012\u4f9d\u8d56\u4e8e\u4e3b\u952e\u3002\u6240\u8c13\u4f20\u9012\u4f9d\u8d56\uff0c\u6307\u7684\u662f\u5982\u679c\u5b58\u5728 <code>A \u2192 B \u2192 C<\/code> \u7684\u51b3\u5b9a\u5173\u7cfb\uff0c\u5219 C \u4f20\u9012\u4f9d\u8d56\u4e8e A\u3002\u56e0\u6b64\uff0c\u6ee1\u8db3\u7b2c\u4e09\u8303\u5f0f\u7684\u6570\u636e\u5e93\u8868\u5e94\u8be5\u4e0d\u5b58\u5728\u5982\u4e0b\u4f9d\u8d56\u5173\u7cfb\uff1a\u4e3b\u952e\u5217 \u2192 \u975e\u4e3b\u952e\u5217 x \u2192 \u975e\u4e3b\u952e\u5217 y<br \/>\n<a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/12\/image-1672209106611.png\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/12\/image-1672209106611.png\" alt=\"file\" \/><\/a><\/p>\n<\/li>\n<\/ul>\n<h4><span class=\"ez-toc-section\" id=\"%E9%99%84%E5%BD%95D_MySQL%E5%94%AF%E4%B8%80%E7%B4%A2%E5%BC%95%E7%BA%A6%E6%9D%9F\"><\/span>\u9644\u5f55D. MySQL\u552f\u4e00\u7d22\u5f15\u7ea6\u675f<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul>\n<li>\u521b\u5efa\u4e00\u5f20\u6d4b\u8bd5\u8868<\/li>\n<\/ul>\n<pre><code class=\"language-sql\">CREATE TABLE test_unique (\n  id int(10) UNIQUE\n) ENGINE=InnoDB;<\/code><\/pre>\n<ul>\n<li>\u63d2\u5165\u6570\u636e<\/li>\n<\/ul>\n<pre><code class=\"language-sql\">INSERT INTO test_unique VALUES(1);\nINSERT INTO test_unique VALUES(5);\nINSERT INTO test_unique VALUES(6);\nINSERT INTO test_unique VALUES(10);\nSELECT * FROM test_unique;<\/code><\/pre>\n<ul>\n<li>\u67e5\u770b\u8868\u7ed3\u6784<\/li>\n<\/ul>\n<p><a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/12\/image-1672280766816.png\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/12\/image-1672280766816.png\" alt=\"file\" \/><\/a><\/p>\n<ul>\n<li>\u6267\u884c\u66f4\u65b0\u64cd\u4f5c<\/li>\n<\/ul>\n<pre><code class=\"language-sql\">UPDATE test_unique\n   SET id = id + 1;<\/code><\/pre>\n<ul>\n<li>\u629b\u51fa\u5f02\u5e38<\/li>\n<\/ul>\n<pre><code>ERROR 1062 (23000): Duplicate entry &#039;6&#039; for key &#039;id&#039;<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>\u8bf4\u660e\uff1a\u672c\u6587\u53c2\u8003\u963f\u91cc\u5df4\u5df4Java\u5f00\u53d1\u624b\u518c\uff0c\u4ee5MySQ&hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":true,"template":"","format":"standard","meta":{"footnotes":""},"categories":[162],"tags":[241,164],"class_list":["post-2394","post","type-post","status-publish","format-standard","hentry","category-162","tag-241","tag-164"],"_links":{"self":[{"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/posts\/2394","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2394"}],"version-history":[{"count":47,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/posts\/2394\/revisions"}],"predecessor-version":[{"id":2993,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/posts\/2394\/revisions\/2993"}],"wp:attachment":[{"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2394"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2394"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2394"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}