{"id":47449,"date":"2023-12-11T15:11:51","date_gmt":"2023-12-11T07:11:51","guid":{"rendered":"https:\/\/wx.kaifamiao.info\/?p=47449"},"modified":"2023-12-11T15:11:51","modified_gmt":"2023-12-11T07:11:51","slug":"%e5%a6%82%e4%bd%95%e8%bf%9b%e8%a1%8csql%e4%bc%98%e5%8c%96%ef%bc%9f-4","status":"publish","type":"post","link":"http:\/\/wx.kaifamiao.info\/index.php\/2023\/12\/11\/%e5%a6%82%e4%bd%95%e8%bf%9b%e8%a1%8csql%e4%bc%98%e5%8c%96%ef%bc%9f-4\/","title":{"rendered":"\u5982\u4f55\u8fdb\u884cSQL\u4f18\u5316\uff1f"},"content":{"rendered":"<p>&#8220;`&#8221;                    <span style=\"\"font-size: 1rem;\"\">\uff081\uff09\u9009\u62e9\u6b63\u786e\u7684\u5b58\u50a8\u5f15\u64ce<\/span><\/p>\n<p>MyISAM \u9002\u5408\u4e8e\u4e00\u4e9b\u9700\u8981\u5927\u91cf\u67e5\u8be2\u7684\u5e94\u7528\uff0c\u4f46\u5176\u5bf9\u4e8e\u6709\u5927\u91cf\u5199\u64cd\u4f5c\u5e76\u4e0d\u662f\u5f88\u597d\u3002\u751a\u81f3\u4f60\u53ea\u662f\u9700\u8981update\u4e00\u4e2a\u5b57\u6bb5\uff0c\u6574\u4e2a\u8868\u90fd\u4f1a\u88ab\u9501\u8d77\u6765\uff0c\u800c\u522b\u7684\u8fdb\u7a0b\uff0c\u5c31\u7b97\u662f\u8bfb\u8fdb\u7a0b\u90fd\u65e0\u6cd5\u64cd\u4f5c\u76f4\u5230\u8bfb\u64cd\u4f5c\u5b8c\u6210\u3002\u53e6\u5916\uff0cMyISAM \u5bf9\u4e8e SELECT COUNT(*) \u8fd9\u7c7b\u7684\u8ba1\u7b97\u662f\u8d85\u5feb\u65e0\u6bd4\u7684\u3002InnoDB \u7684\u8d8b\u52bf\u4f1a\u662f\u4e00\u4e2a\u975e\u5e38\u590d\u6742\u7684\u5b58\u50a8\u5f15\u64ce\uff0c\u5bf9\u4e8e\u4e00\u4e9b\u5c0f\u7684\u5e94\u7528\uff0c\u5b83\u4f1a\u6bd4 MyISAM \u8fd8\u6162\u3002\u4f46\u662f\u5b83\u652f\u6301\u201c\u884c\u9501\u201d \uff0c\u4e8e\u662f\u5728\u5199\u64cd\u4f5c\u6bd4\u8f83\u591a\u7684\u65f6\u5019\uff0c\u4f1a\u66f4\u4f18\u79c0\u3002\u5e76\u4e14\uff0c\u4ed6\u8fd8\u652f\u6301\u66f4\u591a\u7684\u9ad8\u7ea7\u5e94\u7528\uff0c\u6bd4\u5982\uff1a\u4e8b\u52a1\u3002<\/p>\n<p>\uff082\uff09\u4f18\u5316\u5b57\u6bb5\u7684\u6570\u636e\u7c7b\u578b\u8bb0\u4f4f\u4e00\u4e2a\u539f\u5219\uff0c\u8d8a\u5c0f\u7684\u5217\u4f1a\u8d8a\u5feb\u3002\u5982\u679c\u4e00\u4e2a\u8868\u53ea\u4f1a\u6709\u51e0\u5217\u7f62\u4e86\uff08\u6bd4\u5982\u8bf4\u5b57\u5178\u8868\uff0c\u914d\u7f6e\u8868\uff09\uff0c\u90a3\u4e48\uff0c\u6211\u4eec\u5c31\u6ca1\u6709\u7406\u7531\u4f7f\u7528 INT \u6765\u505a\u4e3b\u952e\uff0c\u4f7f\u7528 MEDIUMINT, SMALLINT \u6216\u662f\u66f4\u5c0f\u7684 TINYINT \u4f1a\u66f4\u7ecf\u6d4e\u4e00\u4e9b\u3002\u5982\u679c\u4f60\u4e0d\u9700\u8981\u8bb0\u5f55\u65f6\u95f4\uff0c\u4f7f\u7528 DATE \u8981\u6bd4 DATETIME \u597d\u5f97\u591a\u3002\u5f53\u7136\uff0c\u4f60\u4e5f\u9700\u8981\u7559\u591f\u8db3\u591f\u7684\u6269\u5c55\u7a7a\u95f4\u3002<\/p>\n<p>\uff083\uff09\u4e3a\u641c\u7d22\u5b57\u6bb5\u6dfb\u52a0\u7d22\u5f15\u7d22\u5f15\u5e76\u4e0d\u4e00\u5b9a\u5c31\u662f\u7ed9\u4e3b\u952e\u6216\u662f\u552f\u4e00\u7684\u5b57\u6bb5\u3002\u5982\u679c\u5728\u4f60\u7684\u8868\u4e2d\uff0c\u6709\u67d0\u4e2a\u5b57\u6bb5\u4f60\u603b\u8981\u4f1a\u7ecf\u5e38\u7528\u6765\u505a\u641c\u7d22\uff0c\u90a3\u4e48\u6700\u597d\u662f\u4e3a\u5176\u5efa\u7acb\u7d22\u5f15\uff0c\u9664\u975e\u4f60\u8981\u641c\u7d22\u7684\u5b57\u6bb5\u662f\u5927\u7684\u6587\u672c\u5b57\u6bb5\uff0c\u90a3\u5e94\u8be5\u5efa\u7acb\u5168\u6587\u7d22\u5f15\u3002<\/p>\n<p>\uff084\uff09\u907f\u514d\u4f7f\u7528Select \u4ece\u6570\u636e\u5e93\u91cc\u8bfb\u51fa\u8d8a\u591a\u7684\u6570\u636e\uff0c\u90a3\u4e48\u67e5\u8be2\u5c31\u4f1a\u53d8\u5f97\u8d8a\u6162\u3002\u5e76\u4e14\uff0c\u5982\u679c\u4f60\u7684\u6570\u636e\u5e93\u670d\u52a1\u5668\u548cWEB\u670d\u52a1\u5668\u662f\u4e24\u53f0\u72ec\u7acb\u7684\u670d\u52a1\u5668\u7684\u8bdd\uff0c\u8fd9\u8fd8\u4f1a\u589e\u52a0\u7f51\u7edc\u4f20\u8f93\u7684\u8d1f\u8f7d\u3002\u5373\u4f7f\u4f60\u8981\u67e5\u8be2\u6570\u636e\u8868\u7684\u6240\u6709\u5b57\u6bb5\uff0c\u4e5f\u5c3d\u91cf\u4e0d\u8981\u7528\u901a\u914d\u7b26\uff0c\u5584\u7528\u5185\u7f6e\u63d0\u4f9b\u7684\u5b57\u6bb5\u6392\u9664\u5b9a\u4e49\u4e5f\u8bb8\u80fd\u7ed9\u5e26\u6765\u66f4\u591a\u7684\u4fbf\u5229\u3002<\/p>\n<p>\uff085\uff09\u4f7f\u7528 ENUM \u800c\u4e0d\u662f VARCHARENUM \u7c7b\u578b\u662f\u975e\u5e38\u5feb\u548c\u7d27\u51d1\u7684\u3002\u5728\u5b9e\u9645\u4e0a\uff0c\u5176\u4fdd\u5b58\u7684\u662f TINYINT\uff0c\u4f46\u5176\u5916\u8868\u4e0a\u663e\u793a\u4e3a\u5b57\u7b26\u4e32\u3002\u8fd9\u6837\u4e00\u6765\uff0c\u7528\u8fd9\u4e2a\u5b57\u6bb5\u6765\u505a\u4e00\u4e9b\u9009\u9879\u5217\u8868\u53d8\u5f97\u76f8\u5f53\u7684\u5b8c\u7f8e\u3002\u4f8b\u5982\uff0c\u6027\u522b\u3001\u6c11\u65cf\u3001\u90e8\u95e8\u548c\u72b6\u6001\u4e4b\u7c7b\u7684\u8fd9\u4e9b\u5b57\u6bb5\u7684\u53d6\u503c\u662f\u6709\u9650\u800c\u4e14\u56fa\u5b9a\u7684\uff0c\u90a3\u4e48\uff0c\u4f60\u5e94\u8be5\u4f7f\u7528 ENUM \u800c\u4e0d\u662f VARCHAR\u3002<\/p>\n<p>\uff086\uff09\u5c3d\u53ef\u80fd\u7684\u4f7f\u7528 NOT NULL\u9664\u975e\u4f60\u6709\u4e00\u4e2a\u5f88\u7279\u522b\u7684\u539f\u56e0\u53bb\u4f7f\u7528 NULL \u503c\uff0c\u4f60\u5e94\u8be5\u603b\u662f\u8ba9\u4f60\u7684\u5b57\u6bb5\u4fdd\u6301 NOT NULL\u3002 NULL\u5176\u5b9e\u9700\u8981\u989d\u5916\u7684\u7a7a\u95f4\uff0c\u5e76\u4e14\uff0c\u5728\u4f60\u8fdb\u884c\u6bd4\u8f83\u7684\u65f6\u5019\uff0c\u4f60\u7684\u7a0b\u5e8f\u4f1a\u66f4\u590d\u6742\u3002 \u5f53\u7136\uff0c\u8fd9\u91cc\u5e76\u4e0d\u662f\u8bf4\u4f60\u5c31\u4e0d\u80fd\u4f7f\u7528NULL\u4e86\uff0c\u73b0\u5b9e\u60c5\u51b5\u662f\u5f88\u590d\u6742\u7684\uff0c\u4f9d\u7136\u4f1a\u6709\u4e9b\u60c5\u51b5\u4e0b\uff0c\u4f60\u9700\u8981\u4f7f\u7528NULL\u503c\u3002<\/p>\n<p>\uff087\uff09\u56fa\u5b9a\u957f\u5ea6\u7684\u8868\u4f1a\u66f4\u5feb\u5982\u679c\u8868\u4e2d\u7684\u6240\u6709\u5b57\u6bb5\u90fd\u662f\u201c\u56fa\u5b9a\u957f\u5ea6\u201d\u7684\uff0c\u6574\u4e2a\u8868\u4f1a\u88ab\u8ba4\u4e3a\u662f \u201cstatic\u201d \u6216 \u201cfixed-length\u201d\u3002 \u4f8b\u5982\uff0c\u8868\u4e2d\u6ca1\u6709\u5982\u4e0b\u7c7b\u578b\u7684\u5b57\u6bb5\uff1a VARCHAR\uff0cTEXT\uff0cBLOB\u3002\u53ea\u8981\u4f60\u5305\u62ec\u4e86\u5176\u4e2d\u4e00\u4e2a\u8fd9\u4e9b\u5b57\u6bb5\uff0c\u90a3\u4e48\u8fd9\u4e2a\u8868\u5c31\u4e0d\u662f\u201c\u56fa\u5b9a\u957f\u5ea6\u9759\u6001\u8868\u201d\u4e86\uff0c\u8fd9\u6837\uff0cMySQL \u5f15\u64ce\u4f1a\u7528\u53e6\u4e00\u79cd\u65b9\u6cd5\u6765\u5904\u7406\u3002<\/p>\n<p>\u56fa\u5b9a\u957f\u5ea6\u7684\u8868\u4f1a\u63d0\u9ad8\u6027\u80fd\uff0c\u56e0\u4e3aMySQL\u641c\u5bfb\u5f97\u4f1a\u66f4\u5feb\u4e00\u4e9b\uff0c\u56e0\u4e3a\u8fd9\u4e9b\u56fa\u5b9a\u7684\u957f\u5ea6\u662f\u5f88\u5bb9\u6613\u8ba1\u7b97\u4e0b\u4e00\u4e2a\u6570\u636e\u7684\u504f\u79fb\u91cf\u7684\uff0c\u6240\u4ee5\u8bfb\u53d6\u7684\u81ea\u7136\u4e5f\u4f1a\u5f88\u5feb\u3002\u800c\u5982\u679c\u5b57\u6bb5\u4e0d\u662f\u5b9a\u957f\u7684\uff0c\u90a3\u4e48\uff0c\u6bcf\u4e00\u6b21\u8981\u627e\u4e0b\u4e00\u6761\u7684\u8bdd\uff0c\u9700\u8981\u7a0b\u5e8f\u627e\u5230\u4e3b\u952e\u3002\u5e76\u4e14\uff0c\u56fa\u5b9a\u957f\u5ea6\u7684\u8868\u4e5f\u66f4\u5bb9\u6613\u88ab\u7f13\u5b58\u548c\u91cd\u5efa\u3002\u4e0d\u8fc7\uff0c\u552f\u4e00\u7684\u526f\u4f5c\u7528\u662f\uff0c\u56fa\u5b9a\u957f\u5ea6\u7684\u5b57\u6bb5\u4f1a\u6d6a\u8d39\u4e00\u4e9b\u7a7a\u95f4\uff0c\u56e0\u4e3a\u5b9a\u957f\u7684\u5b57\u6bb5\u65e0\u8bba\u4f60\u7528\u4e0d\u7528\uff0c\u4ed6\u90fd\u662f\u8981\u5206\u914d\u90a3\u4e48\u591a\u7684\u7a7a\u95f4\u3002<\/p>\n<p>&lt;pre&gt;&lt;code&gt;            &quot;&#8220;`<br \/>\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>&#8220;`&#8221; \uff081\uff09\u9009\u62e9\u6b63\u786e\u7684\u5b58\u50a8\u5f15\u64ce MyISAM \u9002\u5408\u4e8e\u4e00\u4e9b\u9700\u8981\u5927\u91cf\u67e5\u8be2\u7684\u5e94\u7528\uff0c\u4f46\u5176\u5bf9\u4e8e [&hellip;]<\/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-47449","post","type-post","status-publish","format-standard","hentry","category-c"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47449","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=47449"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47449\/revisions"}],"predecessor-version":[{"id":47450,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47449\/revisions\/47450"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=47449"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=47449"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=47449"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}