“`” \u8003\u5bdf\u70b9\uff1a\u6570\u636e\u5e93<\/p>\n
\u00a0<\/p>\n
\uff081\uff09\u9009\u53d6\u6700\u9002\u7528\u7684\u5b57\u6bb5\u5c5e\u6027<\/p>\n
MySQL\u53ef\u4ee5\u5f88\u597d\u7684\u652f\u6301\u5927\u6570\u636e\u91cf\u7684\u5b58\u53d6\uff0c\u4f46\u662f\u4e00\u822c\u8bf4\u6765\uff0c\u6570\u636e\u5e93\u4e2d\u7684\u8868\u8d8a\u5c0f\uff0c\u5728\u5b83\u4e0a\u9762\u6267\u884c\u7684\u67e5\u8be2\u4e5f\u5c31\u4f1a\u8d8a\u5feb\u3002\u56e0\u6b64\uff0c\u5728\u521b\u5efa\u8868\u7684\u65f6\u5019\uff0c\u4e3a\u4e86\u83b7\u5f97\u66f4\u597d\u7684\u6027\u80fd\uff0c\u6211\u4eec\u53ef\u4ee5\u5c06\u8868\u4e2d\u5b57\u6bb5\u7684\u5bbd\u5ea6\u8bbe\u5f97\u5c3d\u53ef\u80fd\u5c0f\u3002<\/p>\n
\u4f8b\u5982\uff0c\u5728\u5b9a\u4e49\u90ae\u653f\u7f16\u7801\u8fd9\u4e2a\u5b57\u6bb5\u65f6\uff0c\u5982\u679c\u5c06\u5176\u8bbe\u7f6e\u4e3aCHAR(255),\u663e\u7136\u7ed9\u6570\u636e\u5e93\u589e\u52a0\u4e86\u4e0d\u5fc5\u8981\u7684\u7a7a\u95f4\uff0c\u751a\u81f3\u4f7f\u7528VARCHAR\u8fd9\u79cd\u7c7b\u578b\u4e5f\u662f\u591a\u4f59\u7684\uff0c\u56e0\u4e3aCHAR(6)\u5c31\u53ef\u4ee5\u5f88\u597d\u7684\u5b8c\u6210\u4efb\u52a1\u4e86\u3002\u540c\u6837\u7684\uff0c\u5982\u679c\u53ef\u4ee5\u7684\u8bdd\uff0c\u6211\u4eec\u5e94\u8be5\u4f7f\u7528MEDIUMINT\u800c\u4e0d\u662fBIGIN\u6765\u5b9a\u4e49\u6574\u578b\u5b57\u6bb5\u3002<\/p>\n
\u53e6\u5916\u4e00\u4e2a\u63d0\u9ad8\u6548\u7387\u7684\u65b9\u6cd5\u662f\u5728\u53ef\u80fd\u7684\u60c5\u51b5\u4e0b\uff0c\u5e94\u8be5\u5c3d\u91cf\u628a\u5b57\u6bb5\u8bbe\u7f6e\u4e3aNOTNULL\uff0c\u8fd9\u6837\u5728\u5c06\u6765\u6267\u884c\u67e5\u8be2\u7684\u65f6\u5019\uff0c\u6570\u636e\u5e93\u4e0d\u7528\u53bb\u6bd4\u8f83NULL\u503c\u3002
\n\u5bf9\u4e8e\u67d0\u4e9b\u6587\u672c\u5b57\u6bb5\uff0c\u4f8b\u5982\u201c\u7701\u4efd\u201d\u6216\u8005\u201c\u6027\u522b\u201d\uff0c\u6211\u4eec\u53ef\u4ee5\u5c06\u5b83\u4eec\u5b9a\u4e49\u4e3aENUM\u7c7b\u578b\u3002\u56e0\u4e3a\u5728MySQL\u4e2d\uff0cENUM\u7c7b\u578b\u88ab\u5f53\u4f5c\u6570\u503c\u578b\u6570\u636e\u6765\u5904\u7406\uff0c\u800c\u6570\u503c\u578b\u6570\u636e\u88ab\u5904\u7406\u8d77\u6765\u7684\u901f\u5ea6\u8981\u6bd4\u6587\u672c\u7c7b\u578b\u5feb\u5f97\u591a\u3002\u8fd9\u6837\uff0c\u6211\u4eec\u53c8\u53ef\u4ee5\u63d0\u9ad8\u6570\u636e\u5e93\u7684\u6027\u80fd\u3002<\/p>\n
\uff082\uff09\u4f7f\u7528\u8fde\u63a5\uff08JOIN\uff09\u6765\u4ee3\u66ff\u5b50\u67e5\u8be2(Sub-Queries)<\/p>\n
MySQL\u4ece4.1\u5f00\u59cb\u652f\u6301SQL\u7684\u5b50\u67e5\u8be2\u3002\u8fd9\u4e2a\u6280\u672f\u53ef\u4ee5\u4f7f\u7528SELECT\u8bed\u53e5\u6765\u521b\u5efa\u4e00\u4e2a\u5355\u5217\u7684\u67e5\u8be2\u7ed3\u679c\uff0c\u7136\u540e\u628a\u8fd9\u4e2a\u7ed3\u679c\u4f5c\u4e3a\u8fc7\u6ee4\u6761\u4ef6\u7528\u5728\u53e6\u4e00\u4e2a\u67e5\u8be2\u4e2d\u3002\u4f8b\u5982\uff0c\u6211\u4eec\u8981\u5c06\u5ba2\u6237\u57fa\u672c\u4fe1\u606f\u8868\u4e2d\u6ca1\u6709\u4efb\u4f55\u8ba2\u5355\u7684\u5ba2\u6237\u5220\u9664\u6389\uff0c\u5c31\u53ef\u4ee5\u5229\u7528\u5b50\u67e5\u8be2\u5148\u4ece\u9500\u552e\u4fe1\u606f\u8868\u4e2d\u5c06\u6240\u6709\u53d1\u51fa\u8ba2\u5355\u7684\u5ba2\u6237ID\u53d6\u51fa\u6765\uff0c\u7136\u540e\u5c06\u7ed3\u679c\u4f20\u9012\u7ed9\u4e3b\u67e5\u8be2<\/p>\n
\uff083\uff09\u4f7f\u7528\u8054\u5408(UNION)\u6765\u4ee3\u66ff\u624b\u52a8\u521b\u5efa\u7684\u4e34\u65f6\u8868<\/p>\n
MySQL\u4ece4.0\u7684\u7248\u672c\u5f00\u59cb\u652f\u6301union\u67e5\u8be2\uff0c\u5b83\u53ef\u4ee5\u628a\u9700\u8981\u4f7f\u7528\u4e34\u65f6\u8868\u7684\u4e24\u6761\u6216\u66f4\u591a\u7684select\u67e5\u8be2\u5408\u5e76\u7684\u4e00\u4e2a\u67e5\u8be2\u4e2d\u3002\u5728\u5ba2\u6237\u7aef\u7684\u67e5\u8be2\u4f1a\u8bdd\u7ed3\u675f\u7684\u65f6\u5019\uff0c\u4e34\u65f6\u8868\u4f1a\u88ab\u81ea\u52a8\u5220\u9664\uff0c\u4ece\u800c\u4fdd\u8bc1\u6570\u636e\u5e93\u6574\u9f50\u3001\u9ad8\u6548\u3002\u4f7f\u7528union\u6765\u521b\u5efa\u67e5\u8be2\u7684\u65f6\u5019\uff0c\u6211\u4eec\u53ea\u9700\u8981\u7528UNION\u4f5c\u4e3a\u5173\u952e\u5b57\u628a\u591a\u4e2aselect\u8bed\u53e5\u8fde\u63a5\u8d77\u6765\u5c31\u53ef\u4ee5\u4e86\uff0c\u8981\u6ce8\u610f\u7684\u662f\u6240\u6709select\u8bed\u53e5\u4e2d\u7684\u5b57\u6bb5\u6570\u76ee\u8981\u60f3\u540c\u3002\u4e0b\u9762\u7684\u4f8b\u5b50\u5c31\u6f14\u793a\u4e86\u4e00\u4e2a\u4f7f\u7528UNION\u7684\u67e5\u8be2\u3002<\/p>\n
\uff084\uff09\u4e8b\u52a1<\/p>\n
\u5c3d\u7ba1\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u5b50\u67e5\u8be2\uff08Sub-Queries\uff09\u3001\u8fde\u63a5\uff08JOIN\uff09\u548c\u8054\u5408\uff08UNION\uff09\u6765\u521b\u5efa\u5404\u79cd\u5404\u6837\u7684\u67e5\u8be2\uff0c\u4f46\u4e0d\u662f\u6240\u6709\u7684\u6570\u636e\u5e93\u64cd\u4f5c\u90fd\u53ef\u4ee5\u53ea\u7528\u4e00\u6761\u6216\u5c11\u6570\u51e0\u6761SQL\u8bed\u53e5\u5c31\u53ef\u4ee5\u5b8c\u6210\u7684\u3002\u66f4\u591a\u7684\u65f6\u5019\u662f\u9700\u8981\u7528\u5230\u4e00\u7cfb\u5217\u7684\u8bed\u53e5\u6765\u5b8c\u6210\u67d0\u79cd\u5de5\u4f5c\u3002\u4f46\u662f\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u5f53\u8fd9\u4e2a\u8bed\u53e5\u5757\u4e2d\u7684\u67d0\u4e00\u6761\u8bed\u53e5\u8fd0\u884c\u51fa\u9519\u7684\u65f6\u5019\uff0c\u6574\u4e2a\u8bed\u53e5\u5757\u7684\u64cd\u4f5c\u5c31\u4f1a\u53d8\u5f97\u4e0d\u786e\u5b9a\u8d77\u6765\u3002\u8bbe\u60f3\u4e00\u4e0b\uff0c\u8981\u628a\u67d0\u4e2a\u6570\u636e\u540c\u65f6\u63d2\u5165\u4e24\u4e2a\u76f8\u5173\u8054\u7684\u8868\u4e2d\uff0c\u53ef\u80fd\u4f1a\u51fa\u73b0\u8fd9\u6837\u7684\u60c5\u51b5\uff1a\u7b2c\u4e00\u4e2a\u8868\u4e2d\u6210\u529f\u66f4\u65b0\u540e\uff0c\u6570\u636e\u5e93\u7a81\u7136\u51fa\u73b0\u610f\u5916\u72b6\u51b5\uff0c\u9020\u6210\u7b2c\u4e8c\u4e2a\u8868\u4e2d\u7684\u64cd\u4f5c\u6ca1\u6709\u5b8c\u6210\uff0c\u8fd9\u6837\uff0c\u5c31\u4f1a\u9020\u6210\u6570\u636e\u7684\u4e0d\u5b8c\u6574\uff0c\u751a\u81f3\u4f1a\u7834\u574f\u6570\u636e\u5e93\u4e2d\u7684\u6570\u636e\u3002\u8981\u907f\u514d\u8fd9\u79cd\u60c5\u51b5\uff0c\u5c31\u5e94\u8be5\u4f7f\u7528\u4e8b\u52a1\uff0c\u5b83\u7684\u4f5c\u7528\u662f\uff1a\u8981\u4e48\u8bed\u53e5\u5757\u4e2d\u6bcf\u6761\u8bed\u53e5\u90fd\u64cd\u4f5c\u6210\u529f\uff0c\u8981\u4e48\u90fd\u5931\u8d25\u3002\u6362\u53e5\u8bdd\u8bf4\uff0c\u5c31\u662f\u53ef\u4ee5\u4fdd\u6301\u6570\u636e\u5e93\u4e2d\u6570\u636e\u7684\u4e00\u81f4\u6027\u548c\u5b8c\u6574\u6027\u3002\u4e8b\u7269\u4ee5BEGIN\u5173\u952e\u5b57\u5f00\u59cb\uff0cCOMMIT\u5173\u952e\u5b57\u7ed3\u675f\u3002\u5728\u8fd9\u4e4b\u95f4\u7684\u4e00\u6761SQL\u64cd\u4f5c\u5931\u8d25\uff0c\u90a3\u4e48\uff0cROLLBACK\u547d\u4ee4\u5c31\u53ef\u4ee5\u628a\u6570\u636e\u5e93\u6062\u590d\u5230BEGIN\u5f00\u59cb\u4e4b\u524d\u7684\u72b6\u6001\u3002<\/p>\n
<pre><code> "“`
\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
“`” \u8003\u5bdf\u70b9\uff1a\u6570\u636e\u5e93 \u00a0 \uff081\uff09\u9009\u53d6\u6700\u9002\u7528\u7684\u5b57\u6bb5\u5c5e\u6027 MySQL\u53ef\u4ee5\u5f88\u597d\u7684\u652f\u6301\u5927\u6570\u636e […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-38698","post","type-post","status-publish","format-standard","hentry","category-c"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/38698","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=38698"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/38698\/revisions"}],"predecessor-version":[{"id":38699,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/38698\/revisions\/38699"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=38698"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=38698"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=38698"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}