{"id":79916,"date":"2024-10-16T13:42:14","date_gmt":"2024-10-16T05:42:14","guid":{"rendered":"https:\/\/server.hk\/cnblog\/79916\/"},"modified":"2024-10-16T13:42:14","modified_gmt":"2024-10-16T05:42:14","slug":"mysql%e6%8c%87%e4%bb%a4-substr%ef%bc%88%e6%8f%90%e5%8f%96%e5%ad%90%e4%b8%b2%ef%bc%89","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/79916\/","title":{"rendered":"MySQL\u6307\u4ee4: SUBSTR()\uff08\u63d0\u53d6\u5b50\u4e32\uff09"},"content":{"rendered":"<h1 id=\"mysql%e6%8c%87%e4%bb%a4-substr%ef%bc%88%e6%8f%90%e5%8f%96%e5%ad%90%e4%b8%b2%ef%bc%89-rtniobCiJB\">MySQL\u6307\u4ee4: SUBSTR()\uff08\u63d0\u53d6\u5b50\u4e32\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\u6578\u64da\u3002\u5176\u4e2d\uff0cSUBSTR()\u51fd\u6578\u662f\u4e00\u500b\u975e\u5e38\u5be6\u7528\u7684\u5de5\u5177\uff0c\u7528\u65bc\u63d0\u53d6\u5b57\u7b26\u4e32\u4e2d\u7684\u5b50\u4e32\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0eSUBSTR()\u51fd\u6578\u7684\u7528\u6cd5\u3001\u8a9e\u6cd5\u53ca\u5176\u61c9\u7528\u7bc4\u4f8b\u3002<\/p>\n<h2 id=\"substr%e5%87%bd%e6%95%b8%e6%a6%82%e8%bf%b0-rtniobCiJB\">SUBSTR()\u51fd\u6578\u6982\u8ff0<\/h2>\n<p>SUBSTR()\u51fd\u6578\u7684\u4e3b\u8981\u529f\u80fd\u662f\u5f9e\u4e00\u500b\u5b57\u7b26\u4e32\u4e2d\u63d0\u53d6\u51fa\u6307\u5b9a\u4f4d\u7f6e\u7684\u5b50\u4e32\u3002\u9019\u5728\u8655\u7406\u6587\u672c\u6578\u64da\u6642\u975e\u5e38\u6709\u7528\uff0c\u4f8b\u5982\u5f9e\u7528\u6236\u540d\u4e2d\u63d0\u53d6\u7279\u5b9a\u90e8\u5206\uff0c\u6216\u5f9e\u9577\u5b57\u7b26\u4e32\u4e2d\u7372\u53d6\u6240\u9700\u7684\u4fe1\u606f\u3002<\/p>\n<h2 id=\"%e8%aa%9e%e6%b3%95-rtniobCiJB\">\u8a9e\u6cd5<\/h2>\n<pre><code>SUBSTR(string, start, length)<\/code><\/pre>\n<ul>\n<li><strong>string<\/strong>: \u8981\u63d0\u53d6\u5b50\u4e32\u7684\u539f\u59cb\u5b57\u7b26\u4e32\u3002<\/li>\n<li><strong>start<\/strong>: \u63d0\u53d6\u7684\u8d77\u59cb\u4f4d\u7f6e\uff08\u5f9e1\u958b\u59cb\u8a08\u7b97\uff09\u3002<\/li>\n<li><strong>length<\/strong>: \u8981\u63d0\u53d6\u7684\u5b57\u7b26\u6578\u3002\u5982\u679c\u7701\u7565\uff0c\u5247\u63d0\u53d6\u5230\u5b57\u7b26\u4e32\u7684\u7d50\u5c3e\u3002<\/li>\n<\/ul>\n<h2 id=\"%e4%bd%bf%e7%94%a8%e7%af%84%e4%be%8b-rtniobCiJB\">\u4f7f\u7528\u7bc4\u4f8b<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u4e9b\u4f7f\u7528SUBSTR()\u51fd\u6578\u7684\u7bc4\u4f8b\uff0c\u5e6b\u52a9\u60a8\u66f4\u597d\u5730\u7406\u89e3\u5176\u7528\u6cd5\u3002<\/p>\n<h3 id=\"%e7%af%84%e4%be%8b1-%e6%8f%90%e5%8f%96%e7%94%a8%e6%88%b6%e5%90%8d%e7%9a%84%e4%b8%80%e9%83%a8%e5%88%86-rtniobCiJB\">\u7bc4\u4f8b1: \u63d0\u53d6\u7528\u6236\u540d\u7684\u4e00\u90e8\u5206<\/h3>\n<pre><code>SELECT SUBSTR('username123', 1, 7) AS extracted_username;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u7bc4\u4f8b\u4e2d\uff0c\u6211\u5011\u5f9e\u5b57\u7b26\u4e32&#8217;username123&#8217;\u4e2d\u63d0\u53d6\u4e86\u5f9e\u7b2c\u4e00\u500b\u5b57\u7b26\u958b\u59cb\u7684\u4e03\u500b\u5b57\u7b26\uff0c\u7d50\u679c\u5c07\u662f&#8217;username&#8217;\u3002<\/p>\n<h3 id=\"%e7%af%84%e4%be%8b2-%e6%8f%90%e5%8f%96%e5%ad%97%e7%ac%a6%e4%b8%b2%e7%9a%84%e6%9c%80%e5%be%8c%e5%b9%be%e5%80%8b%e5%ad%97%e7%ac%a6-rtniobCiJB\">\u7bc4\u4f8b2: \u63d0\u53d6\u5b57\u7b26\u4e32\u7684\u6700\u5f8c\u5e7e\u500b\u5b57\u7b26<\/h3>\n<pre><code>SELECT SUBSTR('database', -3) AS last_three_chars;<\/code><\/pre>\n<p>\u9019\u88e1\uff0c\u6211\u5011\u4f7f\u7528\u8ca0\u6578\u4f5c\u70ba\u8d77\u59cb\u4f4d\u7f6e\uff0c\u8868\u793a\u5f9e\u5b57\u7b26\u4e32\u7684\u672b\u5c3e\u958b\u59cb\u63d0\u53d6\u3002\u7d50\u679c\u5c07\u662f&#8217;ase&#8217;\u3002<\/p>\n<h3 id=\"%e7%af%84%e4%be%8b3-%e6%8f%90%e5%8f%96%e4%b8%8d%e6%8c%87%e5%ae%9a%e9%95%b7%e5%ba%a6%e7%9a%84%e5%ad%90%e4%b8%b2-rtniobCiJB\">\u7bc4\u4f8b3: \u63d0\u53d6\u4e0d\u6307\u5b9a\u9577\u5ea6\u7684\u5b50\u4e32<\/h3>\n<pre><code>SELECT SUBSTR('Hello, World!', 8) AS greeting;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u7bc4\u4f8b\u4e2d\uff0c\u6211\u5011\u5f9e\u5b57\u7b26\u4e32&#8217;Hello, World!&#8217;\u7684\u7b2c\u516b\u500b\u5b57\u7b26\u958b\u59cb\u63d0\u53d6\uff0c\u76f4\u5230\u5b57\u7b26\u4e32\u7d50\u5c3e\u3002\u7d50\u679c\u5c07\u662f&#8217;World!&#8217;\u3002<\/p>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-rtniobCiJB\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4f7f\u7528SUBSTR()\u51fd\u6578\u6642\uff0c\u6709\u5e7e\u9ede\u9700\u8981\u6ce8\u610f\uff1a<\/p>\n<ul>\n<li>\u5982\u679c\u8d77\u59cb\u4f4d\u7f6e\u8d85\u904e\u5b57\u7b26\u4e32\u7684\u9577\u5ea6\uff0c\u5247\u8fd4\u56de\u7a7a\u5b57\u7b26\u4e32\u3002<\/li>\n<li>\u5982\u679c\u8d77\u59cb\u4f4d\u7f6e\u70ba\u8ca0\u6578\uff0c\u5247\u5f9e\u5b57\u7b26\u4e32\u7684\u672b\u5c3e\u958b\u59cb\u8a08\u7b97\u3002<\/li>\n<li>\u5982\u679c\u6307\u5b9a\u7684\u9577\u5ea6\u8d85\u904e\u4e86\u5269\u9918\u7684\u5b57\u7b26\u6578\uff0c\u5247\u53ea\u6703\u8fd4\u56de\u5230\u5b57\u7b26\u4e32\u7684\u7d50\u5c3e\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b5%90%e8%ab%96-rtniobCiJB\">\u7d50\u8ad6<\/h2>\n<p>SUBSTR()\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\u7b26\u4e32\u6578\u64da\u3002\u7121\u8ad6\u662f\u63d0\u53d6\u7528\u6236\u540d\u3001\u8655\u7406\u6587\u672c\u9084\u662f\u5206\u6790\u6578\u64da\uff0cSUBSTR()\u90fd\u80fd\u63d0\u4f9b\u6709\u6548\u7684\u89e3\u6c7a\u65b9\u6848\u3002\u638c\u63e1\u9019\u500b\u51fd\u6578\u7684\u4f7f\u7528\uff0c\u5c07\u6709\u52a9\u65bc\u63d0\u5347\u60a8\u7684\u6578\u64da\u8655\u7406\u80fd\u529b\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002\u7121\u8ad6\u662f <a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a> \u9084\u662f <a href=\"https:\/\/server.hk\">\u4e91\u4f3a\u670d\u5668<\/a>\uff0c\u6211\u5011\u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u7a69\u5b9a\u7684\u670d\u52d9\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3MySQL\u6307\u4ee4SUBSTR()\uff0c\u8f7b\u677e\u63d0\u53d6\u5b57\u7b26\u4e32\u4e2d\u7684\u5b50\u4e32\uff0c\u63d0\u5347\u6570\u636e\u5904\u7406\u6548\u7387\uff0c\u4f18\u5316\u67e5\u8be2\u7ed3\u679c\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-79916","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/79916","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=79916"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/79916\/revisions"}],"predecessor-version":[{"id":79917,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/79916\/revisions\/79917"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=79916"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=79916"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=79916"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}