{"id":153379,"date":"2024-11-02T06:57:18","date_gmt":"2024-11-01T22:57:18","guid":{"rendered":"https:\/\/server.hk\/cnblog\/153379\/"},"modified":"2024-11-02T06:57:19","modified_gmt":"2024-11-01T22:57:19","slug":"%e5%be%9e%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e9%81%b8%e6%93%87%e6%95%b8%e6%93%9a%e7%9a%84-from-%e8%aa%9e%e5%8f%a5%e5%8e%9f%e7%90%86%e7%b0%a1%e4%bb%8b-%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e7%9a%84-fr","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/153379\/","title":{"rendered":"\u5f9e\u6578\u64da\u5eab\u4e2d\u9078\u64c7\u6578\u64da\u7684 FROM \u8a9e\u53e5\u539f\u7406\u7c21\u4ecb (\u6578\u64da\u5eab\u4e2d\u7684 FROM)"},"content":{"rendered":"<h1 id=\"%e5%be%9e%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e9%81%b8%e6%93%87%e6%95%b8%e6%93%9a%e7%9a%84-from-%e8%aa%9e%e5%8f%a5%e5%8e%9f%e7%90%86%e7%b0%a1%e4%bb%8b-%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e7%9a%84-fr-KrqoHsFaUH\">\u5f9e\u6578\u64da\u5eab\u4e2d\u9078\u64c7\u6578\u64da\u7684 FROM \u8a9e\u53e5\u539f\u7406\u7c21\u4ecb (\u6578\u64da\u5eab\u4e2d\u7684 FROM)<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u67e5\u8a62\u4e2d\uff0c<code>FROM<\/code> \u8a9e\u53e5\u662f SQL \u8a9e\u8a00\u4e2d\u4e0d\u53ef\u6216\u7f3a\u7684\u4e00\u90e8\u5206\u3002\u5b83\u7684\u4e3b\u8981\u529f\u80fd\u662f\u6307\u5b9a\u67e5\u8a62\u6240\u9700\u7684\u6578\u64da\u4f86\u6e90\uff0c\u901a\u5e38\u662f\u6578\u64da\u8868\u3002\u7406\u89e3 <code>FROM<\/code> \u8a9e\u53e5\u7684\u539f\u7406\u5c0d\u65bc\u6709\u6548\u5730\u64b0\u5beb SQL \u67e5\u8a62\u81f3\u95dc\u91cd\u8981\u3002<\/p>\n<h2>1. <code>FROM<\/code> \u8a9e\u53e5\u7684\u57fa\u672c\u7d50\u69cb<\/h2>\n<p>\u5728 SQL \u67e5\u8a62\u4e2d\uff0c<code>FROM<\/code> \u8a9e\u53e5\u901a\u5e38\u4f4d\u65bc\u67e5\u8a62\u7684\u4e2d\u9593\u90e8\u5206\uff0c\u8207 <code>SELECT<\/code> \u548c <code>WHERE<\/code> \u8a9e\u53e5\u76f8\u4e92\u914d\u5408\u3002\u5176\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>SELECT column1, column2\nFROM table_name\nWHERE condition;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c<code>table_name<\/code> \u662f\u6578\u64da\u4f86\u6e90\u7684\u540d\u7a31\uff0c\u800c <code>column1<\/code> \u548c <code>column2<\/code> \u5247\u662f\u9700\u8981\u9078\u64c7\u7684\u5217\u3002<\/p>\n<h2 id=\"2-%e5%a4%9a%e8%a1%a8%e6%9f%a5%e8%a9%a2-KrqoHsFaUH\">2. \u591a\u8868\u67e5\u8a62<\/h2>\n<p>\u5728\u5be6\u969b\u61c9\u7528\u4e2d\uff0c\u6578\u64da\u5f80\u5f80\u5206\u6563\u5728\u591a\u500b\u8868\u4e2d\u3002\u9019\u6642\u5019\uff0c<code>FROM<\/code> \u8a9e\u53e5\u53ef\u4ee5\u7528\u4f86\u9032\u884c\u591a\u8868\u67e5\u8a62\u3002\u53ef\u4ee5\u4f7f\u7528\u5167\u806f\u63a5\uff08INNER JOIN\uff09\u3001\u5916\u806f\u63a5\uff08OUTER JOIN\uff09\u7b49\u65b9\u5f0f\u4f86\u9023\u63a5\u591a\u500b\u8868\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT a.column1, b.column2\nFROM table_a AS a\nINNER JOIN table_b AS b ON a.common_field = b.common_field;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c<code>table_a<\/code> \u548c <code>table_b<\/code> \u900f\u904e\u5171\u540c\u7684\u5b57\u6bb5\u9032\u884c\u9023\u63a5\uff0c\u5f9e\u800c\u9078\u64c7\u6240\u9700\u7684\u6578\u64da\u3002<\/p>\n<h2 id=\"3-%e4%bd%bf%e7%94%a8%e5%88%a5%e5%90%8d-KrqoHsFaUH\">3. \u4f7f\u7528\u5225\u540d<\/h2>\n<p>\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u5225\u540d\u53ef\u4ee5\u63d0\u9ad8\u53ef\u8b80\u6027\uff0c\u7279\u5225\u662f\u5728\u6d89\u53ca\u591a\u500b\u8868\u7684\u60c5\u6cc1\u4e0b\u3002\u4f7f\u7528 <code>AS<\/code> \u95dc\u9375\u5b57\u53ef\u4ee5\u70ba\u8868\u6216\u5217\u6307\u5b9a\u5225\u540d\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT a.column1 AS alias1, b.column2 AS alias2\nFROM table_a AS a\nJOIN table_b AS b ON a.id = b.a_id;<\/code><\/pre>\n<p>\u9019\u6a23\u7684\u5beb\u6cd5\u4f7f\u5f97\u67e5\u8a62\u7d50\u679c\u66f4\u6613\u65bc\u7406\u89e3\u3002<\/p>\n<h2>4. \u5b50\u67e5\u8a62\u4e2d\u7684 <code>FROM<\/code> \u8a9e\u53e5<\/h2>\n<p>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0c<code>FROM<\/code> \u8a9e\u53e5\u4e5f\u53ef\u4ee5\u7528\u65bc\u5b50\u67e5\u8a62\u3002\u9019\u610f\u5473\u8457\u53ef\u4ee5\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u5d4c\u5957\u53e6\u4e00\u500b\u67e5\u8a62\u3002\u4f8b\u5982\uff1a<\/p>\n<pre><code>SELECT *\nFROM (SELECT column1, column2 FROM table_name WHERE condition) AS subquery;<\/code><\/pre>\n<p>\u9019\u6a23\u7684\u67e5\u8a62\u53ef\u4ee5\u8b93\u6211\u5011\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u4f7f\u7528\u53e6\u4e00\u500b\u67e5\u8a62\u7684\u7d50\u679c\uff0c\u5f9e\u800c\u5be6\u73fe\u66f4\u8907\u96dc\u7684\u6578\u64da\u9078\u64c7\u3002<\/p>\n<h2>5. <code>FROM<\/code> \u8a9e\u53e5\u7684\u6027\u80fd\u8003\u91cf<\/h2>\n<p>\u5728\u8a2d\u8a08\u6578\u64da\u5eab\u67e5\u8a62\u6642\uff0c<code>FROM<\/code> \u8a9e\u53e5\u7684\u9078\u64c7\u6703\u5f71\u97ff\u67e5\u8a62\u7684\u6027\u80fd\u3002\u4f7f\u7528\u9069\u7576\u7684\u7d22\u5f15\u3001\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u5168\u8868\u6383\u63cf\u4ee5\u53ca\u5408\u7406\u8a2d\u8a08\u8868\u7d50\u69cb\u90fd\u662f\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u7684\u91cd\u8981\u56e0\u7d20\u3002<\/p>\n<h2 id=\"%e7%b8%bd%e7%b5%90-KrqoHsFaUH\">\u7e3d\u7d50<\/h2>\n<p>\u7e3d\u7684\u4f86\u8aaa\uff0c<code>FROM<\/code> \u8a9e\u53e5\u5728 SQL \u67e5\u8a62\u4e2d\u626e\u6f14\u8457\u95dc\u9375\u89d2\u8272\uff0c\u7121\u8ad6\u662f\u55ae\u8868\u67e5\u8a62\u9084\u662f\u591a\u8868\u67e5\u8a62\uff0c\u90fd\u9700\u8981\u6b63\u78ba\u4f7f\u7528 <code>FROM<\/code> \u4f86\u6307\u5b9a\u6578\u64da\u4f86\u6e90\u3002\u900f\u904e\u7406\u89e3\u5176\u57fa\u672c\u7d50\u69cb\u3001\u4f7f\u7528\u5225\u540d\u3001\u9032\u884c\u5b50\u67e5\u8a62\u4ee5\u53ca\u8003\u91cf\u6027\u80fd\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u64b0\u5beb\u51fa\u66f4\u9ad8\u6548\u7684 SQL \u67e5\u8a62\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc\u6578\u64da\u5eab\u7ba1\u7406\u6216\u5176\u4ed6\u6280\u8853\u554f\u984c\u6709\u8208\u8da3\uff0c\u6b61\u8fce\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4e86\u89e3\u66f4\u591a\u8cc7\u8a0a\uff0c\u7279\u5225\u662f\u6211\u5011\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u670d\u52d9\uff0c\u70ba\u60a8\u7684\u61c9\u7528\u63d0\u4f9b\u7a69\u5b9a\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u6578\u64da\u5eab\u4e2d FROM \u8a9e\u53e5\u7684\u539f\u7406\uff0c\u63a2\u7d22\u5982\u4f55\u9078\u64c7\u548c\u63d0\u53d6\u6578\u64da\uff0c\u63d0\u5347\u67e5\u8a62\u6548\u7387\u8207\u6e96\u78ba\u6027\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-153379","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/153379","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=153379"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/153379\/revisions"}],"predecessor-version":[{"id":153380,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/153379\/revisions\/153380"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=153379"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=153379"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=153379"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}