{"id":79130,"date":"2024-10-16T12:47:17","date_gmt":"2024-10-16T04:47:17","guid":{"rendered":"https:\/\/server.hk\/cnblog\/79130\/"},"modified":"2024-10-16T12:47:17","modified_gmt":"2024-10-16T04:47:17","slug":"mysql%e6%8c%87%e4%bb%a4-mid%ef%bc%88%e4%b8%ad%e9%96%93%e6%88%aa%e5%8f%96%ef%bc%89","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/79130\/","title":{"rendered":"MySQL\u6307\u4ee4: MID()\uff08\u4e2d\u9593\u622a\u53d6\uff09"},"content":{"rendered":"<h1 id=\"mysql%e6%8c%87%e4%bb%a4-mid%ef%bc%88%e4%b8%ad%e9%96%93%e6%88%aa%e5%8f%96%ef%bc%89-nyEpDcPCWP\">MySQL\u6307\u4ee4: MID()\uff08\u4e2d\u9593\u622a\u53d6\uff09<\/h1>\n<p>\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u4e2d\uff0cMySQL\u662f\u4e00\u500b\u5ee3\u6cdb\u4f7f\u7528\u7684\u95dc\u806f\u5f0f\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\u3002\u5b83\u63d0\u4f9b\u4e86\u591a\u7a2e\u529f\u80fd\u5f37\u5927\u7684\u6307\u4ee4\u4f86\u8655\u7406\u548c\u64cd\u4f5c\u8cc7\u6599\u3002\u5176\u4e2d\uff0cMID()\u51fd\u6578\u662f\u4e00\u500b\u975e\u5e38\u5be6\u7528\u7684\u5de5\u5177\uff0c\u80fd\u5920\u5f9e\u4e00\u500b\u5b57\u4e32\u4e2d\u63d0\u53d6\u51fa\u7279\u5b9a\u7684\u5b50\u5b57\u4e32\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0eMID()\u51fd\u6578\u7684\u7528\u6cd5\u53ca\u5176\u61c9\u7528\u7bc4\u4f8b\u3002<\/p>\n<h2 id=\"mid%e5%87%bd%e6%95%b8%e7%9a%84%e5%9f%ba%e6%9c%ac%e8%aa%9e%e6%b3%95-nyEpDcPCWP\">MID()\u51fd\u6578\u7684\u57fa\u672c\u8a9e\u6cd5<\/h2>\n<p>MID()\u51fd\u6578\u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>MID(string, start, length)<\/code><\/pre>\n<ul>\n<li><strong>string<\/strong>: \u8981\u9032\u884c\u622a\u53d6\u7684\u539f\u59cb\u5b57\u4e32\u3002<\/li>\n<li><strong>start<\/strong>: \u958b\u59cb\u622a\u53d6\u7684\u4f4d\u7f6e\uff0c\u5f9e1\u958b\u59cb\u8a08\u7b97\u3002<\/li>\n<li><strong>length<\/strong>: \u8981\u622a\u53d6\u7684\u5b57\u5143\u6578\u91cf\u3002<\/li>\n<\/ul>\n<h2 id=\"%e4%bd%bf%e7%94%a8mid%e5%87%bd%e6%95%b8%e7%9a%84%e7%af%84%e4%be%8b-nyEpDcPCWP\">\u4f7f\u7528MID()\u51fd\u6578\u7684\u7bc4\u4f8b<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u4e9b\u4f7f\u7528MID()\u51fd\u6578\u7684\u7bc4\u4f8b\uff0c\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u5176\u7528\u6cd5\u3002<\/p>\n<h3 id=\"%e7%af%84%e4%be%8b1-%e5%9f%ba%e6%9c%ac%e6%88%aa%e5%8f%96-nyEpDcPCWP\">\u7bc4\u4f8b1: \u57fa\u672c\u622a\u53d6<\/h3>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba<code>users<\/code>\u7684\u8cc7\u6599\u8868\uff0c\u5176\u4e2d\u6709\u4e00\u500b<code>username<\/code>\u6b04\u4f4d\uff0c\u5167\u5bb9\u70ba\u300cJohnDoe\u300d\u3002\u5982\u679c\u6211\u5011\u60f3\u8981\u63d0\u53d6\u300cJohn\u300d\u9019\u500b\u5b57\u4e32\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u6307\u4ee4\uff1a<\/p>\n<pre><code>SELECT MID(username, 1, 4) AS first_name FROM users;<\/code><\/pre>\n<p>\u9019\u689d\u6307\u4ee4\u5c07\u8fd4\u56de\u300cJohn\u300d\uff0c\u56e0\u70ba\u5b83\u5f9e\u7b2c\u4e00\u500b\u5b57\u5143\u958b\u59cb\uff0c\u622a\u53d6\u4e86\u56db\u500b\u5b57\u5143\u3002<\/p>\n<h3 id=\"%e7%af%84%e4%be%8b2-%e5%be%9e%e4%b8%ad%e9%96%93%e9%96%8b%e5%a7%8b%e6%88%aa%e5%8f%96-nyEpDcPCWP\">\u7bc4\u4f8b2: \u5f9e\u4e2d\u9593\u958b\u59cb\u622a\u53d6<\/h3>\n<p>\u5982\u679c\u6211\u5011\u60f3\u8981\u5f9e\u300cJohnDoe\u300d\u4e2d\u63d0\u53d6\u300cDoe\u300d\uff0c\u53ef\u4ee5\u9019\u6a23\u505a\uff1a<\/p>\n<pre><code>SELECT MID(username, 5, 3) AS last_name FROM users;<\/code><\/pre>\n<p>\u9019\u689d\u6307\u4ee4\u5c07\u8fd4\u56de\u300cDoe\u300d\uff0c\u56e0\u70ba\u5b83\u5f9e\u7b2c\u4e94\u500b\u5b57\u5143\u958b\u59cb\uff0c\u622a\u53d6\u4e86\u4e09\u500b\u5b57\u5143\u3002<\/p>\n<h3 id=\"%e7%af%84%e4%be%8b3-%e4%bd%bf%e7%94%a8%e8%ae%8a%e6%95%b8-nyEpDcPCWP\">\u7bc4\u4f8b3: \u4f7f\u7528\u8b8a\u6578<\/h3>\n<p>\u5728\u5be6\u969b\u61c9\u7528\u4e2d\uff0c\u6211\u5011\u53ef\u80fd\u9700\u8981\u4f7f\u7528\u8b8a\u6578\u4f86\u52d5\u614b\u5730\u9032\u884c\u622a\u53d6\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>SET @start = 1;\nSET @length = 4;\nSELECT MID(username, @start, @length) AS first_name FROM users;<\/code><\/pre>\n<p>\u9019\u6a23\uff0c\u6211\u5011\u53ef\u4ee5\u6839\u64da\u8b8a\u6578\u7684\u503c\u4f86\u9748\u6d3b\u5730\u622a\u53d6\u5b57\u4e32\u3002<\/p>\n<h2 id=\"mid%e5%87%bd%e6%95%b8%e7%9a%84%e6%87%89%e7%94%a8%e5%a0%b4%e6%99%af-nyEpDcPCWP\">MID()\u51fd\u6578\u7684\u61c9\u7528\u5834\u666f<\/h2>\n<p>MID()\u51fd\u6578\u5728\u8a31\u591a\u5834\u666f\u4e2d\u90fd\u975e\u5e38\u6709\u7528\uff0c\u4f8b\u5982\uff1a<\/p>\n<ul>\n<li><strong>\u8cc7\u6599\u6e05\u7406<\/strong>: \u5728\u8655\u7406\u4e0d\u898f\u5247\u7684\u5b57\u4e32\u6642\uff0c\u53ef\u4ee5\u4f7f\u7528MID()\u4f86\u63d0\u53d6\u6240\u9700\u7684\u90e8\u5206\u3002<\/li>\n<li><strong>\u5831\u544a\u751f\u6210<\/strong>: \u5728\u751f\u6210\u5831\u544a\u6642\uff0c\u53ef\u80fd\u9700\u8981\u5f9e\u9577\u5b57\u4e32\u4e2d\u63d0\u53d6\u7279\u5b9a\u7684\u8cc7\u8a0a\u3002<\/li>\n<li><strong>\u7528\u6236\u754c\u9762\u986f\u793a<\/strong>: \u5728\u986f\u793a\u7528\u6236\u540d\u7a31\u6216\u5176\u4ed6\u8cc7\u8a0a\u6642\uff0c\u53ef\u4ee5\u4f7f\u7528MID()\u4f86\u9650\u5236\u986f\u793a\u7684\u5b57\u5143\u6578\u91cf\u3002<\/li>\n<\/ul>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-nyEpDcPCWP\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4f7f\u7528MID()\u51fd\u6578\u6642\uff0c\u6709\u5e7e\u9ede\u9700\u8981\u6ce8\u610f\uff1a<\/p>\n<ul>\n<li>\u5982\u679c<code>start<\/code>\u7684\u503c\u5927\u65bc\u5b57\u4e32\u7684\u9577\u5ea6\uff0c\u5247\u8fd4\u56de\u7a7a\u5b57\u4e32\u3002<\/li>\n<li>\u5982\u679c<code>length<\/code>\u7684\u503c\u70ba\u8ca0\u6578\uff0c\u5247\u8fd4\u56de\u7a7a\u5b57\u4e32\u3002<\/li>\n<li>\u5982\u679c<code>length<\/code>\u7684\u503c\u8d85\u904e\u5269\u9918\u5b57\u5143\u7684\u6578\u91cf\uff0c\u5247\u53ea\u6703\u8fd4\u56de\u5269\u9918\u7684\u5b57\u5143\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-nyEpDcPCWP\">\u7e3d\u7d50<\/h2>\n<p>MID()\u51fd\u6578\u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u80fd\u5920\u5e6b\u52a9\u958b\u767c\u8005\u5728MySQL\u4e2d\u9748\u6d3b\u5730\u8655\u7406\u5b57\u4e32\u3002\u7121\u8ad6\u662f\u5728\u8cc7\u6599\u6e05\u7406\u3001\u5831\u544a\u751f\u6210\u9084\u662f\u7528\u6236\u754c\u9762\u986f\u793a\u4e2d\uff0cMID()\u90fd\u80fd\u767c\u63ee\u91cd\u8981\u4f5c\u7528\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u7ba1\u7406\u8cc7\u6599\u7684\u4f01\u696d\u4f86\u8aaa\uff0c\u9078\u64c7\u5408\u9069\u7684\u8cc7\u6599\u5eab\u89e3\u6c7a\u65b9\u6848\u81f3\u95dc\u91cd\u8981\u3002\u82e5\u60a8\u5c0d\u65bc<code>VPS<\/code>\u3001<code>\u9999\u6e2fVPS<\/code>\u6216\u5176\u4ed6<code>\u4e91\u670d\u52a1\u5668<\/code>\u7684\u9700\u6c42\u6709\u8208\u8da3\uff0c\u6b61\u8fce\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9 <a href=\"https:\/\/server.hk\">Server.HK<\/a> \u7372\u53d6\u66f4\u591a\u8cc7\u8a0a\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3MySQL\u4e2d\u7684MID()\u6307\u4ee4\uff0c\u5b78\u7fd2\u5982\u4f55\u5f9e\u5b57\u7b26\u4e32\u4e2d\u63d0\u53d6\u7279\u5b9a\u4f4d\u7f6e\u7684\u5b50\u5b57\u7b26\u4e32\uff0c\u63d0\u5347\u6578\u64da\u8655\u7406\u6548\u7387\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-79130","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/79130","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=79130"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/79130\/revisions"}],"predecessor-version":[{"id":79131,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/79130\/revisions\/79131"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=79130"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=79130"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=79130"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}