{"id":168471,"date":"2024-11-06T12:39:25","date_gmt":"2024-11-06T04:39:25","guid":{"rendered":"https:\/\/server.hk\/cnblog\/168471\/"},"modified":"2024-11-06T12:39:26","modified_gmt":"2024-11-06T04:39:26","slug":"sql-%e8%aa%9e%e5%8f%a5%e4%b8%ad%e7%9a%84%e5%b5%8c%e5%a5%97-select-%e8%aa%9e%e5%8f%a5","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/168471\/","title":{"rendered":"SQL \u8a9e\u53e5\u4e2d\u7684\u5d4c\u5957 SELECT \u8a9e\u53e5"},"content":{"rendered":"<h1 id=\"sql-%e8%aa%9e%e5%8f%a5%e4%b8%ad%e7%9a%84%e5%b5%8c%e5%a5%97-select-%e8%aa%9e%e5%8f%a5-dVTECIVHwL\">SQL \u8a9e\u53e5\u4e2d\u7684\u5d4c\u5957 SELECT \u8a9e\u53e5<\/h1>\n<p>\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\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\u5d4c\u5957 SELECT \u8a9e\u53e5\uff08\u4e5f\u7a31\u70ba\u5b50\u67e5\u8a62\uff09\u662f SQL \u4e2d\u4e00\u500b\u5f37\u5927\u7684\u529f\u80fd\uff0c\u5141\u8a31\u7528\u6236\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u5d4c\u5165\u53e6\u4e00\u500b\u67e5\u8a62\u3002\u9019\u7a2e\u6280\u8853\u53ef\u4ee5\u7528\u4f86\u89e3\u6c7a\u8907\u96dc\u7684\u67e5\u8a62\u9700\u6c42\uff0c\u4e26\u63d0\u9ad8\u8cc7\u6599\u6aa2\u7d22\u7684\u9748\u6d3b\u6027\u548c\u6548\u7387\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af%e5%b5%8c%e5%a5%97-select-%e8%aa%9e%e5%8f%a5%ef%bc%9f-dVTECIVHwL\">\u4ec0\u9ebc\u662f\u5d4c\u5957 SELECT \u8a9e\u53e5\uff1f<\/h2>\n<p>\u5d4c\u5957 SELECT \u8a9e\u53e5\u662f\u6307\u5728\u4e00\u500b SELECT \u8a9e\u53e5\u4e2d\u5305\u542b\u53e6\u4e00\u500b SELECT \u8a9e\u53e5\u3002\u9019\u7a2e\u7d50\u69cb\u4f7f\u5f97\u7528\u6236\u53ef\u4ee5\u5728\u4e3b\u67e5\u8a62\u4e2d\u4f7f\u7528\u5b50\u67e5\u8a62\u7684\u7d50\u679c\u3002\u5b50\u67e5\u8a62\u53ef\u4ee5\u51fa\u73fe\u5728 SELECT\u3001FROM\u3001WHERE \u548c HAVING \u5b50\u53e5\u4e2d\uff0c\u4e26\u4e14\u53ef\u4ee5\u8fd4\u56de\u55ae\u4e00\u503c\u6216\u591a\u500b\u503c\u3002<\/p>\n<h2 id=\"%e5%b5%8c%e5%a5%97-select-%e8%aa%9e%e5%8f%a5%e7%9a%84%e9%a1%9e%e5%9e%8b-dVTECIVHwL\">\u5d4c\u5957 SELECT \u8a9e\u53e5\u7684\u985e\u578b<\/h2>\n<ul>\n<li><strong>\u55ae\u884c\u5b50\u67e5\u8a62\uff1a<\/strong>\u8fd4\u56de\u55ae\u4e00\u503c\u7684\u5b50\u67e5\u8a62\uff0c\u901a\u5e38\u7528\u65bc WHERE \u5b50\u53e5\u4e2d\u3002<\/li>\n<li><strong>\u591a\u884c\u5b50\u67e5\u8a62\uff1a<\/strong>\u8fd4\u56de\u591a\u500b\u503c\u7684\u5b50\u67e5\u8a62\uff0c\u901a\u5e38\u7528\u65bc IN \u6216 EXISTS \u5b50\u53e5\u4e2d\u3002<\/li>\n<li><strong>\u76f8\u95dc\u5b50\u67e5\u8a62\uff1a<\/strong>\u9019\u7a2e\u5b50\u67e5\u8a62\u4f9d\u8cf4\u65bc\u5916\u90e8\u67e5\u8a62\u7684\u503c\uff0c\u901a\u5e38\u7528\u65bc WHERE \u5b50\u53e5\u4e2d\u3002<\/li>\n<li><strong>\u975e\u76f8\u95dc\u5b50\u67e5\u8a62\uff1a<\/strong>\u9019\u7a2e\u5b50\u67e5\u8a62\u4e0d\u4f9d\u8cf4\u65bc\u5916\u90e8\u67e5\u8a62\u7684\u503c\uff0c\u53ef\u4ee5\u7368\u7acb\u57f7\u884c\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%b5%8c%e5%a5%97-select-%e8%aa%9e%e5%8f%a5%e7%9a%84%e7%af%84%e4%be%8b-dVTECIVHwL\">\u5d4c\u5957 SELECT \u8a9e\u53e5\u7684\u7bc4\u4f8b<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u7bc4\u4f8b\uff0c\u5c55\u793a\u5982\u4f55\u4f7f\u7528\u5d4c\u5957 SELECT \u8a9e\u53e5\u4f86\u67e5\u8a62\u8cc7\u6599\u3002<\/p>\n<pre><code>SELECT employee_id, employee_name\nFROM employees\nWHERE department_id = (\n    SELECT department_id\n    FROM departments\n    WHERE department_name = 'Sales'\n);\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u7bc4\u4f8b\u4e2d\uff0c\u4e3b\u67e5\u8a62\u5f9e <code>employees<\/code> \u8868\u4e2d\u9078\u64c7\u54e1\u5de5 ID \u548c\u59d3\u540d\uff0c\u800c\u5b50\u67e5\u8a62\u5247\u5f9e <code>departments<\/code> \u8868\u4e2d\u9078\u64c7\u90e8\u9580 ID\u3002\u53ea\u6709\u7576\u54e1\u5de5\u7684\u90e8\u9580 ID \u8207\u5b50\u67e5\u8a62\u8fd4\u56de\u7684\u90e8\u9580 ID \u76f8\u7b26\u6642\uff0c\u8a72\u54e1\u5de5\u7684\u8cc7\u6599\u624d\u6703\u88ab\u9078\u53d6\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8%e5%b5%8c%e5%a5%97-select-%e8%aa%9e%e5%8f%a5%e7%9a%84%e5%84%aa%e5%8b%a2-dVTECIVHwL\">\u4f7f\u7528\u5d4c\u5957 SELECT \u8a9e\u53e5\u7684\u512a\u52e2<\/h2>\n<p>\u4f7f\u7528\u5d4c\u5957 SELECT \u8a9e\u53e5\u6709\u5e7e\u500b\u660e\u986f\u7684\u512a\u52e2\uff1a<\/p>\n<ul>\n<li><strong>\u63d0\u9ad8\u67e5\u8a62\u7684\u9748\u6d3b\u6027\uff1a<\/strong>\u5d4c\u5957\u67e5\u8a62\u5141\u8a31\u7528\u6236\u6839\u64da\u5176\u4ed6\u67e5\u8a62\u7684\u7d50\u679c\u4f86\u7be9\u9078\u8cc7\u6599\uff0c\u9019\u5728\u8655\u7406\u8907\u96dc\u7684\u8cc7\u6599\u95dc\u4fc2\u6642\u7279\u5225\u6709\u7528\u3002<\/li>\n<li><strong>\u7c21\u5316\u67e5\u8a62\u7d50\u69cb\uff1a<\/strong>\u901a\u904e\u5c07\u67e5\u8a62\u5206\u89e3\u70ba\u591a\u500b\u90e8\u5206\uff0c\u7528\u6236\u53ef\u4ee5\u66f4\u6e05\u6670\u5730\u7406\u89e3\u6bcf\u500b\u67e5\u8a62\u7684\u76ee\u7684\u548c\u7d50\u679c\u3002<\/li>\n<li><strong>\u589e\u5f37\u53ef\u8b80\u6027\uff1a<\/strong>\u5d4c\u5957\u67e5\u8a62\u53ef\u4ee5\u4f7f SQL \u8a9e\u53e5\u66f4\u5177\u53ef\u8b80\u6027\uff0c\u7279\u5225\u662f\u5728\u8655\u7406\u591a\u500b\u8868\u4e4b\u9593\u7684\u95dc\u806f\u6642\u3002<\/li>\n<\/ul>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-dVTECIVHwL\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5118\u7ba1\u5d4c\u5957 SELECT \u8a9e\u53e5\u63d0\u4f9b\u4e86\u8a31\u591a\u512a\u52e2\uff0c\u4f46\u5728\u4f7f\u7528\u6642\u4e5f\u9700\u8981\u6ce8\u610f\u4ee5\u4e0b\u5e7e\u9ede\uff1a<\/p>\n<ul>\n<li>\u6027\u80fd\u554f\u984c\uff1a\u904e\u591a\u7684\u5d4c\u5957\u67e5\u8a62\u53ef\u80fd\u6703\u5c0e\u81f4\u6027\u80fd\u4e0b\u964d\uff0c\u7279\u5225\u662f\u5728\u8655\u7406\u5927\u91cf\u8cc7\u6599\u6642\u3002<\/li>\n<li>\u53ef\u7dad\u8b77\u6027\uff1a\u904e\u65bc\u8907\u96dc\u7684\u5d4c\u5957\u67e5\u8a62\u53ef\u80fd\u6703\u4f7f SQL \u8a9e\u53e5\u96e3\u4ee5\u7dad\u8b77\u548c\u7406\u89e3\u3002<\/li>\n<li>\u8cc7\u6599\u4e00\u81f4\u6027\uff1a\u78ba\u4fdd\u5b50\u67e5\u8a62\u8fd4\u56de\u7684\u8cc7\u6599\u662f\u6b63\u78ba\u7684\uff0c\u4ee5\u907f\u514d\u4e3b\u67e5\u8a62\u51fa\u73fe\u932f\u8aa4\u7684\u7d50\u679c\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-dVTECIVHwL\">\u7e3d\u7d50<\/h2>\n<p>\u5d4c\u5957 SELECT \u8a9e\u53e5\u662f SQL \u4e2d\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u80fd\u5920\u5e6b\u52a9\u7528\u6236\u5728\u8907\u96dc\u7684\u8cc7\u6599\u67e5\u8a62\u4e2d\u63d0\u9ad8\u9748\u6d3b\u6027\u548c\u6548\u7387\u3002\u901a\u904e\u5408\u7406\u4f7f\u7528\u5d4c\u5957\u67e5\u8a62\uff0c\u7528\u6236\u53ef\u4ee5\u66f4\u6709\u6548\u5730\u5f9e\u8cc7\u6599\u5eab\u4e2d\u6aa2\u7d22\u6240\u9700\u7684\u8cc7\u6599\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u8cc7\u6599\u8655\u7406\u7684\u61c9\u7528\u5834\u666f\uff0c\u9078\u64c7\u5408\u9069\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u6216 <a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a> \u89e3\u6c7a\u65b9\u6848\uff0c\u53ef\u4ee5\u9032\u4e00\u6b65\u63d0\u5347\u8cc7\u6599\u5eab\u7684\u6027\u80fd\u548c\u7a69\u5b9a\u6027\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3 SQL \u8a9e\u53e5\u4e2d\u7684\u5d4c\u5957 SELECT \u8a9e\u53e5\uff0c\u638c\u63e1\u5982\u4f55\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u5b50\u67e5\u8a62\u4ee5\u63d0\u9ad8\u6578\u64da\u6aa2\u7d22\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-168471","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168471","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=168471"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168471\/revisions"}],"predecessor-version":[{"id":168472,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/168471\/revisions\/168472"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=168471"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=168471"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=168471"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}