{"id":363,"date":"2023-09-16T10:44:50","date_gmt":"2023-09-16T02:44:50","guid":{"rendered":""},"modified":"2023-09-18T11:50:02","modified_gmt":"2023-09-18T03:50:02","slug":"sql%e6%88%aa%e5%8f%96%e5%ad%97%e7%ac%a6%e4%b8%b2%e5%90%88%e8%be%91","status":"publish","type":"post","link":"https:\/\/mushiming.com\/363.html","title":{"rendered":"SQL\u622a\u53d6\u5b57\u7b26\u4e32\u5408\u8f91"},"content":{"rendered":"<p><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"display: none;\"> \n <path stroke-linecap=\"round\" d=\"M5,0 0,2.5 5,5z\" id=\"raphael-marker-block\" style=\"-webkit-tap-highlight-color: rgba(0, 0, 0, 0);\"><\/path> \n<\/svg> <\/p>\n<div class=\"toc\">\n<h3>\u6587\u7ae0\u76ee\u5f55<\/h3>\n<ul>\n<li>\n<ul>\n<li>\n<ul>\n<li>1. substring_index<\/li>\n<li>2. left\/right\/mid\/substring<\/li>\n<li><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/div>\n<h3>1. substring_index<\/h3>\n<ul>\n<li>\u8bed\u6cd5\uff1a<code>substring_index(\u5b57\u7b26\u4e32\uff0c\u5206\u9694\u7b26\uff0c\u5e8f\u53f7k)<\/code>\uff1a\u4ece\u4ee5\u5206\u9694\u7b26\u5206\u9694\u7684\u5b57\u7b26\u4e32\u5f53\u4e2d\u53d6\u7b2ck\u4e2a\u5b57\u7b26<\/li>\n<\/ul>\n<p><code>\u9002\u7528\u4e8e\u542b\u6709\u5206\u9694\u7b26\u7684\u5b57\u7b26\u4e32<\/code><\/p>\n<pre><code class=\"prism language-sql\"><span class=\"token keyword\">select<\/span> substring_index<span class=\"token punctuation\">(<\/span>profile<span class=\"token punctuation\">,<\/span><span class=\"token string\">','<\/span><span class=\"token punctuation\">,<\/span><span class=\"token string\">'-1'<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">as<\/span> gender<span class=\"token punctuation\">,<\/span><span class=\"token function\">count<\/span><span class=\"token punctuation\">(<\/span>device_id<span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">as<\/span> number\n<span class=\"token keyword\">from<\/span> user_submit\n<span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> gender\n<\/code><\/pre>\n<p>\u6ce8\u610f\uff1a<code>\u53ef\u4ee5\u5d4c\u5957\u4f7f\u7528<\/code>\u3002\u56e0\u4e3a<code>substring_index\u9009\u62e9\u7684\u662f\u4e00\u90e8\u5206\u5b57\u7b26\u4e32<\/code>\uff0c\u4f8b\u5982\u5b57\u7b26\u4e32hh=\u2018a,b,cc,dd\u2019\uff0c\u60f3\u8981\u9009\u53d6cc\uff0c\u5982\u679c\u4f7f\u7528substring_index(hh,\u2018,\u2019,-2)\u5219\u7ed3\u679c\u4e3a\u2019c,dd\u2019\uff0c\u56e0\u6b64\u9700\u8981\u518d\u8fdb\u884c\u4e00\u6b21substring_index\u622a\u53d6\u5b57\u7b26\u4e32<\/p>\n<pre><code class=\"prism language-sql\"><span class=\"token keyword\">select<\/span> substring_index<span class=\"token punctuation\">(<\/span>substring_index<span class=\"token punctuation\">(<\/span>profile<span class=\"token punctuation\">,<\/span><span class=\"token string\">','<\/span><span class=\"token punctuation\">,<\/span><span class=\"token operator\">-<\/span><span class=\"token number\">2<\/span><span class=\"token punctuation\">)<\/span><span class=\"token punctuation\">,<\/span><span class=\"token string\">','<\/span><span class=\"token punctuation\">,<\/span><span class=\"token number\">1<\/span><span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">as<\/span> age<span class=\"token punctuation\">,<\/span><span class=\"token function\">count<\/span><span class=\"token punctuation\">(<\/span>device_id<span class=\"token punctuation\">)<\/span> <span class=\"token keyword\">as<\/span> number\n<span class=\"token keyword\">from<\/span> user_submit\n<span class=\"token keyword\">group<\/span> <span class=\"token keyword\">by<\/span> age\n<span class=\"token keyword\">order<\/span> <span class=\"token keyword\">by<\/span> age <span class=\"token keyword\">desc<\/span>\n<\/code><\/pre>\n<h3>2. left\/right\/mid\/substring<\/h3>\n<ul>\n<li><code>left(string,len)<\/code>:\u622a\u53d6\u5b57\u7b26\u4e32\u4ece\u5de6\u8fb9\u5f00\u59cb\u7684len\u4e2a\u5b57\u7b26<\/li>\n<li><code>right(string,len) <\/code>\uff1a\u622a\u53d6\u5b57\u7b26\u4e32\u4ece\u53f3\u8fb9\u5f00\u59cb\u7684len\u4e2a\u5b57\u7b26<\/li>\n<li><code>mid(string,start,len)<\/code>\uff1a\u4ece\u6307\u5b9a\u5f00\u59cb\u7684\u5730\u65b9\u5f00\u59cb\u622a\u53d6len\u4e2a\u5b57\u7b26<\/li>\n<li><code>substring(string,start,len)<\/code>\uff1a\u548cmid\u7528\u6cd5\u7c7b\u4f3c<\/li>\n<\/ul>\n<h3><\/h3>\n","protected":false},"excerpt":{"rendered":"SQL\u4e2d\u622a\u53d6\u5b57\u7b26\u4e32_sql\u6309\u5206\u9694\u7b26\u622a\u53d6","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[82],"tags":[],"_links":{"self":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts\/363"}],"collection":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/comments?post=363"}],"version-history":[{"count":0,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts\/363\/revisions"}],"wp:attachment":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/media?parent=363"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/categories?post=363"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/tags?post=363"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}