{"id":189364,"date":"2024-11-12T07:04:18","date_gmt":"2024-11-11T23:04:18","guid":{"rendered":"https:\/\/server.hk\/cnblog\/189364\/"},"modified":"2024-11-12T07:04:19","modified_gmt":"2024-11-11T23:04:19","slug":"%e5%90%8c%e4%b8%80%e5%88%97sql%e5%ad%97%e7%ac%a6%e4%b8%b2%e7%9b%b8%e5%8a%a0%e7%9a%84%e6%96%b9%e6%b3%95","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/189364\/","title":{"rendered":"\u540c\u4e00\u5217SQL\u5b57\u7b26\u4e32\u76f8\u52a0\u7684\u65b9\u6cd5"},"content":{"rendered":"<h1 id=\"%e5%90%8c%e4%b8%80%e5%88%97sql%e5%ad%97%e7%ac%a6%e4%b8%b2%e7%9b%b8%e5%8a%a0%e7%9a%84%e6%96%b9%e6%b3%95-VsbpWPIBAM\">\u540c\u4e00\u5217SQL\u5b57\u7b26\u4e32\u76f8\u52a0\u7684\u65b9\u6cd5<\/h1>\n<p>\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u4e2d\uff0cSQL\uff08\u7d50\u69cb\u5316\u67e5\u8a62\u8a9e\u8a00\uff09\u662f\u4e00\u7a2e\u7528\u65bc\u67e5\u8a62\u548c\u64cd\u4f5c\u8cc7\u6599\u7684\u6a19\u6e96\u8a9e\u8a00\u3002\u7576\u6211\u5011\u9700\u8981\u5c07\u540c\u4e00\u5217\u4e2d\u7684\u591a\u500b\u5b57\u7b26\u4e32\u9032\u884c\u76f8\u52a0\u6642\uff0cSQL\u63d0\u4f9b\u4e86\u591a\u7a2e\u65b9\u6cd5\u4f86\u5be6\u73fe\u9019\u4e00\u529f\u80fd\u3002\u672c\u6587\u5c07\u63a2\u8a0e\u5e7e\u7a2e\u5e38\u898b\u7684\u5b57\u7b26\u4e32\u76f8\u52a0\u65b9\u6cd5\uff0c\u4e26\u63d0\u4f9b\u76f8\u61c9\u7684\u793a\u4f8b\u4ee3\u78bc\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8-concat-%e5%87%bd%e6%95%b8-VsbpWPIBAM\">\u4f7f\u7528 CONCAT \u51fd\u6578<\/h2>\n<p>\u5728\u8a31\u591a\u8cc7\u6599\u5eab\u7cfb\u7d71\u4e2d\uff0c<code>CONCAT<\/code> \u51fd\u6578\u662f\u6700\u5e38\u7528\u7684\u5b57\u7b26\u4e32\u76f8\u52a0\u65b9\u6cd5\u3002\u9019\u500b\u51fd\u6578\u53ef\u4ee5\u63a5\u53d7\u591a\u500b\u53c3\u6578\uff0c\u4e26\u5c07\u5b83\u5011\u9023\u63a5\u6210\u4e00\u500b\u5b57\u7b26\u4e32\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528 <code>CONCAT<\/code> \u51fd\u6578\u7684\u57fa\u672c\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>SELECT CONCAT(column1, column2, ...) AS concatenated_string FROM table_name;<\/code><\/pre>\n<p>\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba <code>employees<\/code> \u7684\u8868\u683c\uff0c\u5176\u4e2d\u5305\u542b <code>first_name<\/code> \u548c <code>last_name<\/code> \u5169\u5217\uff0c\u6211\u5011\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u67e5\u8a62\u4f86\u5c07\u9019\u5169\u5217\u7684\u5b57\u7b26\u4e32\u76f8\u52a0\uff1a<\/p>\n<pre><code>SELECT CONCAT(first_name, ' ', last_name) AS full_name FROM employees;<\/code><\/pre>\n<h2 id=\"%e4%bd%bf%e7%94%a8-%e9%81%8b%e7%ae%97%e7%ac%a6-VsbpWPIBAM\">\u4f7f\u7528 || \u904b\u7b97\u7b26<\/h2>\n<p>\u5728\u67d0\u4e9b\u8cc7\u6599\u5eab\u7cfb\u7d71\uff08\u5982 PostgreSQL \u548c SQLite\uff09\u4e2d\uff0c\u53ef\u4ee5\u4f7f\u7528 <code>||<\/code> \u904b\u7b97\u7b26\u4f86\u9032\u884c\u5b57\u7b26\u4e32\u7684\u9023\u63a5\u3002\u9019\u7a2e\u65b9\u6cd5\u7684\u8a9e\u6cd5\u76f8\u5c0d\u7c21\u55ae\uff0c\u4ee5\u4e0b\u662f\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT first_name || ' ' || last_name AS full_name FROM employees;<\/code><\/pre>\n<p>\u9019\u6a23\u7684\u67e5\u8a62\u5c07\u8fd4\u56de\u6bcf\u4f4d\u54e1\u5de5\u7684\u5168\u540d\uff0c\u4e26\u4e14\u8207\u4f7f\u7528 <code>CONCAT<\/code> \u51fd\u6578\u7684\u7d50\u679c\u76f8\u540c\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8-group_concat-%e5%87%bd%e6%95%b8-VsbpWPIBAM\">\u4f7f\u7528 GROUP_CONCAT \u51fd\u6578<\/h2>\n<p>\u7576\u9700\u8981\u5c07\u540c\u4e00\u5217\u4e2d\u7684\u591a\u500b\u503c\u5408\u4f75\u70ba\u4e00\u500b\u5b57\u7b26\u4e32\u6642\uff0c<code>GROUP_CONCAT<\/code> \u51fd\u6578\u975e\u5e38\u6709\u7528\u3002\u9019\u500b\u51fd\u6578\u901a\u5e38\u7528\u65bc\u805a\u5408\u67e5\u8a62\u4e2d\uff0c\u80fd\u5920\u5c07\u591a\u884c\u6578\u64da\u5408\u4f75\u70ba\u4e00\u884c\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528 <code>GROUP_CONCAT<\/code> \u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT department, GROUP_CONCAT(employee_name SEPARATOR ', ') AS employees FROM employees GROUP BY department;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6211\u5011\u5c07\u6bcf\u500b\u90e8\u9580\u7684\u54e1\u5de5\u59d3\u540d\u5408\u4f75\u70ba\u4e00\u500b\u5b57\u7b26\u4e32\uff0c\u4e26\u7528\u9017\u865f\u5206\u9694\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8-string_agg-%e5%87%bd%e6%95%b8-VsbpWPIBAM\">\u4f7f\u7528 STRING_AGG \u51fd\u6578<\/h2>\n<p>\u5728 SQL Server \u548c PostgreSQL \u4e2d\uff0c<code>STRING_AGG<\/code> \u51fd\u6578\u63d0\u4f9b\u4e86\u4e00\u7a2e\u66f4\u9748\u6d3b\u7684\u65b9\u5f0f\u4f86\u5408\u4f75\u5b57\u7b26\u4e32\u3002\u9019\u500b\u51fd\u6578\u5141\u8a31\u7528\u6236\u6307\u5b9a\u5206\u9694\u7b26\uff0c\u4e26\u4e14\u53ef\u4ee5\u8655\u7406\u66f4\u8907\u96dc\u7684\u60c5\u6cc1\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528 <code>STRING_AGG<\/code> \u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT department, STRING_AGG(employee_name, ', ') AS employees FROM employees GROUP BY department;<\/code><\/pre>\n<p>\u9019\u6a23\u7684\u67e5\u8a62\u5c07\u8fd4\u56de\u6bcf\u500b\u90e8\u9580\u7684\u54e1\u5de5\u59d3\u540d\uff0c\u4e26\u7528\u9017\u865f\u5206\u9694\uff0c\u8207 <code>GROUP_CONCAT<\/code> \u7684\u529f\u80fd\u985e\u4f3c\uff0c\u4f46\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\u63d0\u4f9b\u4e86\u66f4\u597d\u7684\u6027\u80fd\u548c\u9748\u6d3b\u6027\u3002<\/p>\n<h2 id=\"%e7%b5%90%e8%ab%96-VsbpWPIBAM\">\u7d50\u8ad6<\/h2>\n<p>\u5728SQL\u4e2d\uff0c\u5b57\u7b26\u4e32\u76f8\u52a0\u7684\u65b9\u6cd5\u6709\u5f88\u591a\uff0c\u6839\u64da\u4e0d\u540c\u7684\u9700\u6c42\u548c\u8cc7\u6599\u5eab\u7cfb\u7d71\uff0c\u53ef\u4ee5\u9078\u64c7\u6700\u5408\u9069\u7684\u65b9\u5f0f\u3002\u7121\u8ad6\u662f\u4f7f\u7528 <code>CONCAT<\/code> \u51fd\u6578\u3001<code>||<\/code> \u904b\u7b97\u7b26\u3001<code>GROUP_CONCAT<\/code> \u9084\u662f <code>STRING_AGG<\/code> \u51fd\u6578\uff0c\u9019\u4e9b\u65b9\u6cd5\u90fd\u80fd\u6709\u6548\u5730\u5e6b\u52a9\u6211\u5011\u8655\u7406\u5b57\u7b26\u4e32\u6578\u64da\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc\u8cc7\u6599\u5eab\u7ba1\u7406\u6216\u5176\u4ed6\u76f8\u95dc\u6280\u8853\u6709\u9032\u4e00\u6b65\u7684\u9700\u6c42\uff0c\u6b61\u8fce\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4e86\u89e3\u66f4\u591a\u8cc7\u8a0a\u3002\u6211\u5011\u63d0\u4f9b\u5404\u7a2e <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0c\u5e6b\u52a9\u60a8\u66f4\u597d\u5730\u7ba1\u7406\u60a8\u7684\u6578\u64da\u548c\u61c9\u7528\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22\u5728SQL\u4e2d\u5982\u4f55\u5c06\u540c\u4e00\u5217\u7684\u5b57\u7b26\u4e32\u76f8\u52a0\uff0c\u63d0\u5347\u6570\u636e\u5904\u7406\u6548\u7387\uff0c\u7b80\u5316\u67e5\u8be2\u64cd\u4f5c\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-189364","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/189364","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=189364"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/189364\/revisions"}],"predecessor-version":[{"id":189365,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/189364\/revisions\/189365"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=189364"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=189364"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=189364"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}