{"id":201093,"date":"2025-05-06T09:32:41","date_gmt":"2025-05-06T01:32:41","guid":{"rendered":"https:\/\/server.hk\/cnblog\/201093\/"},"modified":"2025-05-06T09:32:41","modified_gmt":"2025-05-06T01:32:41","slug":"sql-%e6%9f%a5%e8%af%a2%e4%b8%ad%e5%a6%82%e4%bd%95%e4%bc%98%e9%9b%85%e5%9c%b0%e6%b6%88%e9%99%a4%e9%87%8d%e5%a4%8d%e5%ad%97%e6%ae%b5%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/201093\/","title":{"rendered":"SQL \u67e5\u8be2\u4e2d\u5982\u4f55\u4f18\u96c5\u5730\u6d88\u9664\u91cd\u590d\u5b57\u6bb5\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<h1>SQL \u67e5\u8be2\u4e2d\u5982\u4f55\u4f18\u96c5\u5730\u6d88\u9664\u91cd\u590d\u5b57\u6bb5\uff1f<\/h1>\n<p>\u6b22\u8fce\u5404\u4f4d\u5c0f\u4f19\u4f34\u6765\u5230\u4e3b\u673a\u5b9d\u8d1d\uff0c\u76f8\u805a\u4e8e\u6b64\u90fd\u662f\u7f18\u54c8\u54c8\u54c8\uff01\u4eca\u5929\u6211\u7ed9\u5927\u5bb6\u5e26\u6765\uff0c\u8fd9\u7bc7\u6587\u7ae0\u4e3b\u8981\u8bb2\u5230\u7b49\u7b49\u77e5\u8bc6\uff0c\u5982\u679c\u4f60\u5bf9\u76f8\u5173\u7684\u77e5\u8bc6\u975e\u5e38\u611f\u5174\u8da3\u6216\u8005\u6b63\u5728\u81ea\u5b66\uff0c\u90fd\u53ef\u4ee5\u5173\u6ce8\u6211\uff0c\u6211\u4f1a\u6301\u7eed\u66f4\u65b0\u76f8\u5173\u6587\u7ae0\uff01\u5f53\u7136\uff0c\u6709\u4ec0\u4e48\u5efa\u8bae\u4e5f\u6b22\u8fce\u5728\u8bc4\u8bba\u7559\u8a00\u63d0\u51fa\uff01\u4e00\u8d77\u5b66\u4e60\uff01<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241130\/1732976691674b20330ba0d.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>\u5982\u4f55\u6d88\u9664 sql \u67e5\u8be2\u4e2d\u7684\u91cd\u590d\u5b57\u6bb5\uff1f<\/strong><\/p>\n<p>\u5728\u4e00\u4e2a sql \u8fde\u8868\u67e5\u8be2\u4e2d\uff0c\u7ecf\u5e38\u4f1a\u51fa\u73b0\u91cd\u590d\u5b57\u6bb5\u7684\u95ee\u9898\uff0c\u6bd4\u5982\u5916\u952e\u6216\u5171\u4eab\u5217\u3002\u4e3a\u4e86\u53bb\u9664\u8fd9\u4e9b\u91cd\u590d\u5b57\u6bb5\uff0c\u901a\u5e38\u4f1a\u4f7f\u7528 distinct \u5173\u952e\u5b57\u6216\u663e\u5f0f\u6307\u5b9a\u67e5\u8be2\u5b57\u6bb5\u3002\u4e0d\u8fc7\uff0c\u8fd8\u6709\u4e00\u79cd\u66f4\u7b80\u6d01\u7684\u65b9\u6cd5\uff1a\u4f7f\u7528 using \u5173\u952e\u5b57\u8fdb\u884c\u8fde\u63a5\u3002<\/p>\n<p><strong>using \u5173\u952e\u5b57<\/strong><\/p>\n<p>using \u5173\u952e\u5b57\u5141\u8bb8\u5728\u8fde\u63a5\u8868\u65f6\u6307\u5b9a\u5171\u4eab\u5217\uff0c\u800c\u4e0d\u5fc5\u663e\u5f0f\u5217\u51fa\u5b83\u4eec\u3002\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre>select * from \u88681 left join \u88682 using(\u5171\u4eab\u5217);<\/pre>\n<p><strong>\u793a\u4f8b<\/strong><\/p>\n<p>\u5728\u95ee\u9898\u4e2d\u7ed9\u51fa\u7684\u793a\u4f8b\u4e2d\uff0cstudent \u8868\u548c score \u8868\u901a\u8fc7 s_id \u5217\u8fde\u63a5\u3002\u4f7f\u7528 distinct \u5173\u952e\u5b57\u53bb\u9664\u91cd\u590d\u5b57\u6bb5\u7684\u67e5\u8be2\u4e3a\uff1a<\/p>\n<pre>select distinct * from student stu left join score sco on stu.s_id = sco.s_id;<\/pre>\n<p>\u800c\u4f7f\u7528 using \u5173\u952e\u5b57\u7684\u67e5\u8be2\u5219\u66f4\u4e3a\u7b80\u6d01\uff1a<\/p>\n<pre>select * from student stu left join score sco using(s_id);<\/pre>\n<p>\u7ec8\u4e8e\u4ecb\u7ecd\u5b8c\u5566\uff01\u5c0f\u4f19\u4f34\u4eec\uff0c\u8fd9\u7bc7\u5173\u4e8e\u300aSQL \u67e5\u8be2\u4e2d\u5982\u4f55\u4f18\u96c5\u5730\u6d88\u9664\u91cd\u590d\u5b57\u6bb5\uff1f\u300b\u7684\u4ecb\u7ecd\u5e94\u8be5\u8ba9\u4f60\u6536\u83b7\u591a\u591a\u4e86\u5427\uff01\u6b22\u8fce\u5927\u5bb6\u6536\u85cf\u6216\u5206\u4eab\u7ed9\u66f4\u591a\u9700\u8981\u5b66\u4e60\u7684\u670b\u53cb\u5427~\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\u4e5f\u4f1a\u53d1\u5e03\u6570\u636e\u5e93\u76f8\u5173\u77e5\u8bc6\uff0c\u5feb\u6765\u5173\u6ce8\u5427\uff01<\/p>\n<dl>\n<dt>\n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"<p>SQL \u67e5\u8be2\u4e2d\u5982\u4f55\u4f18\u96c5\u5730\u6d88\u9664\u91cd\u590d&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-201093","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/201093","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"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=201093"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/201093\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=201093"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=201093"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=201093"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}