{"id":186392,"date":"2024-11-11T05:32:19","date_gmt":"2024-11-10T21:32:19","guid":{"rendered":"https:\/\/server.hk\/cnblog\/186392\/"},"modified":"2024-11-11T05:32:20","modified_gmt":"2024-11-10T21:32:20","slug":"%e6%95%b8%e6%93%9a%e5%ba%ab%e7%9a%84%e5%8d%8a%e9%80%a3%e6%8e%a5%ef%bc%9a%e5%af%a6%e7%8f%besemi-join%ef%bc%88%e6%95%b8%e6%93%9a%e5%ba%absemi-join%e5%af%a6%e7%8f%be%ef%bc%89","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/186392\/","title":{"rendered":"\u6578\u64da\u5eab\u7684\u534a\u9023\u63a5\uff1a\u5be6\u73fesemi join\uff08\u6578\u64da\u5eabsemi join\u5be6\u73fe\uff09"},"content":{"rendered":"<h1 id=\"%e6%95%b8%e6%93%9a%e5%ba%ab%e7%9a%84%e5%8d%8a%e9%80%a3%e6%8e%a5%ef%bc%9a%e5%af%a6%e7%8f%besemi-join%ef%bc%88%e6%95%b8%e6%93%9a%e5%ba%absemi-join%e5%af%a6%e7%8f%be%ef%bc%89-ZCnWouCvDF\">\u6578\u64da\u5eab\u7684\u534a\u9023\u63a5\uff1a\u5be6\u73fesemi join\uff08\u6578\u64da\u5eabsemi 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id=\"%e4%bb%80%e9%ba%bc%e6%98%af%e5%8d%8a%e9%80%a3%e6%8e%a5%ef%bc%88semi-join%ef%bc%89%ef%bc%9f-ZCnWouCvDF\">\u4ec0\u9ebc\u662f\u534a\u9023\u63a5\uff08Semi Join\uff09\uff1f<\/h2>\n<p>\u534a\u9023\u63a5\u662f\u4e00\u7a2e\u7279\u6b8a\u7684\u9023\u63a5\u64cd\u4f5c\uff0c\u4e3b\u8981\u7528\u65bc\u67e5\u8a62\u4e2d\u53ea\u9700\u8981\u77e5\u9053\u67d0\u4e9b\u884c\u662f\u5426\u5b58\u5728\u65bc\u53e6\u4e00\u500b\u8868\u4e2d\uff0c\u800c\u4e0d\u9700\u8981\u8fd4\u56de\u9019\u4e9b\u884c\u7684\u5177\u9ad4\u6578\u64da\u3002\u9019\u7a2e\u64cd\u4f5c\u901a\u5e38\u7528\u65bc\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\uff0c\u56e0\u70ba\u5b83\u53ef\u4ee5\u6e1b\u5c11\u9700\u8981\u8655\u7406\u7684\u6578\u64da\u91cf\u3002<\/p>\n<p>\u4f8b\u5982\uff0c\u5047\u8a2d\u6709\u5169\u500b\u8868\uff1a<code>Customers<\/code>\uff08\u5ba2\u6236\uff09\u548c<code>Orders<\/code>\uff08\u8a02\u55ae\uff09\u3002\u5982\u679c\u6211\u5011\u60f3\u67e5\u8a62\u6240\u6709\u6709\u4e0b\u8a02\u55ae\u7684\u5ba2\u6236\uff0c\u6211\u5011\u53ef\u4ee5\u4f7f\u7528\u534a\u9023\u63a5\u4f86\u7372\u53d6\u5ba2\u6236ID\uff0c\u800c\u4e0d\u9700\u8981\u8fd4\u56de\u6240\u6709\u8a02\u55ae\u7684\u8a73\u7d30\u4fe1\u606f\u3002<\/p>\n<h2 id=\"%e5%8d%8a%e9%80%a3%e6%8e%a5%e7%9a%84%e5%af%a6%e7%8f%be%e6%96%b9%e5%bc%8f-ZCnWouCvDF\">\u534a\u9023\u63a5\u7684\u5be6\u73fe\u65b9\u5f0f<\/h2>\n<p>\u5728 SQL \u4e2d\uff0c\u534a\u9023\u63a5\u53ef\u4ee5\u901a\u904e\u4f7f\u7528 EXISTS \u6216 IN \u5b50\u53e5\u4f86\u5be6\u73fe\u3002\u4ee5\u4e0b\u662f\u5169\u7a2e\u5e38\u898b\u7684\u5be6\u73fe\u65b9\u5f0f\uff1a<\/p>\n<h3 id=\"%e4%bd%bf%e7%94%a8-exists-ZCnWouCvDF\">\u4f7f\u7528 EXISTS<\/h3>\n<pre><code>SELECT DISTINCT c.CustomerID\nFROM Customers c\nWHERE EXISTS (\n    SELECT 1\n    FROM Orders o\n    WHERE o.CustomerID = c.CustomerID\n);\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6211\u5011\u9078\u64c7\u4e86\u6240\u6709\u5b58\u5728\u65bc <code>Orders<\/code> \u8868\u4e2d\u7684\u5ba2\u6236ID\u3002\u4f7f\u7528 EXISTS \u5b50\u53e5\u53ef\u4ee5\u6709\u6548\u5730\u6aa2\u67e5\u6bcf\u500b\u5ba2\u6236\u662f\u5426\u6709\u8a02\u55ae\u3002<\/p>\n<h3 id=\"%e4%bd%bf%e7%94%a8-in-ZCnWouCvDF\">\u4f7f\u7528 IN<\/h3>\n<pre><code>SELECT DISTINCT c.CustomerID\nFROM Customers c\nWHERE c.CustomerID IN (\n    SELECT o.CustomerID\n    FROM Orders o\n);\n<\/code><\/pre>\n<p>\u9019\u500b\u67e5\u8a62\u4f7f\u7528 IN \u5b50\u53e5\u4f86\u7372\u53d6\u6240\u6709\u6709\u8a02\u55ae\u7684\u5ba2\u6236ID\u3002\u9019\u7a2e\u65b9\u6cd5\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\u53ef\u80fd\u6703\u6bd4 EXISTS \u66f4\u6709\u6548\uff0c\u5177\u9ad4\u53d6\u6c7a\u65bc\u6578\u64da\u5eab\u7684\u67e5\u8a62\u512a\u5316\u5668\u3002<\/p>\n<h2 id=\"%e5%8d%8a%e9%80%a3%e6%8e%a5%e7%9a%84%e5%84%aa%e5%8b%a2-ZCnWouCvDF\">\u534a\u9023\u63a5\u7684\u512a\u52e2<\/h2>\n<ul>\n<li><strong>\u6027\u80fd\u63d0\u5347\uff1a<\/strong>\u534a\u9023\u63a5\u53ef\u4ee5\u986f\u8457\u6e1b\u5c11\u67e5\u8a62\u6240\u9700\u7684\u6578\u64da\u91cf\uff0c\u5f9e\u800c\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002<\/li>\n<li><strong>\u7c21\u5316\u67e5\u8a62\uff1a<\/strong>\u901a\u904e\u53ea\u6aa2\u67e5\u5b58\u5728\u6027\uff0c\u534a\u9023\u63a5\u53ef\u4ee5\u4f7f\u67e5\u8a62\u66f4\u7c21\u6f54\uff0c\u6613\u65bc\u7406\u89e3\u3002<\/li>\n<li><strong>\u8cc7\u6e90\u7bc0\u7701\uff1a<\/strong>\u6e1b\u5c11\u4e0d\u5fc5\u8981\u7684\u6578\u64da\u50b3\u8f38\u548c\u8655\u7406\uff0c\u5f9e\u800c\u7bc0\u7701\u7cfb\u7d71\u8cc7\u6e90\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%8d%8a%e9%80%a3%e6%8e%a5%e7%9a%84%e6%87%89%e7%94%a8%e5%a0%b4%e6%99%af-ZCnWouCvDF\">\u534a\u9023\u63a5\u7684\u61c9\u7528\u5834\u666f<\/h2>\n<p>\u534a\u9023\u63a5\u5728\u8a31\u591a\u5834\u666f\u4e2d\u90fd\u975e\u5e38\u6709\u7528\uff0c\u7279\u5225\u662f\u5728\u9700\u8981\u6aa2\u67e5\u6578\u64da\u5b58\u5728\u6027\u800c\u4e0d\u9700\u8981\u5177\u9ad4\u6578\u64da\u7684\u60c5\u6cc1\u4e0b\u3002\u4f8b\u5982\uff1a<\/p>\n<ul>\n<li>\u7528\u65bc\u5831\u544a\u751f\u6210\u6642\uff0c\u50c5\u9700\u78ba\u8a8d\u67d0\u4e9b\u689d\u4ef6\u662f\u5426\u6eff\u8db3\u3002<\/li>\n<li>\u5728\u6578\u64da\u6e05\u7406\u904e\u7a0b\u4e2d\uff0c\u6aa2\u67e5\u67d0\u4e9b\u8a18\u9304\u662f\u5426\u5b58\u5728\u65bc\u5176\u4ed6\u8868\u4e2d\u3002<\/li>\n<li>\u5728\u6578\u64da\u5206\u6790\u4e2d\uff0c\u5feb\u901f\u7be9\u9078\u51fa\u7b26\u5408\u689d\u4ef6\u7684\u6578\u64da\u96c6\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-ZCnWouCvDF\">\u7e3d\u7d50<\/h2>\n<p>\u534a\u9023\u63a5\u662f\u4e00\u7a2e\u9ad8\u6548\u7684\u67e5\u8a62\u6280\u8853\uff0c\u80fd\u5920\u5728\u4e0d\u8fd4\u56de\u6240\u6709\u5339\u914d\u884c\u7684\u60c5\u6cc1\u4e0b\uff0c\u5f9e\u4e00\u500b\u8868\u4e2d\u9078\u64c7\u8207\u53e6\u4e00\u500b\u8868\u76f8\u95dc\u7684\u884c\u3002\u901a\u904e\u4f7f\u7528 EXISTS \u6216 IN \u5b50\u53e5\uff0c\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u80fd\u5920\u6709\u6548\u5730\u6aa2\u67e5\u6578\u64da\u7684\u5b58\u5728\u6027\uff0c\u5f9e\u800c\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u548c\u8cc7\u6e90\u5229\u7528\u7387\u3002\u5728\u7576\u4eca\u6578\u64da\u9a45\u52d5\u7684\u74b0\u5883\u4e2d\uff0c\u638c\u63e1\u534a\u9023\u63a5\u7684\u5be6\u73fe\u65b9\u5f0f\u5c0d\u65bc\u6578\u64da\u5eab\u958b\u767c\u8005\u548c\u7ba1\u7406\u8005\u4f86\u8aaa\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\uff0c\u8003\u616e\u4f7f\u7528<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u6216<a href=\"https:\/\/server.hk\">\u9999\u6e2f\u4f3a\u670d\u5668<\/a>\u4f86\u652f\u6301\u60a8\u7684\u61c9\u7528\u7a0b\u5e8f\u548c\u6578\u64da\u7ba1\u7406\u9700\u6c42\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u63a2\u7d22\u6578\u64da\u5eab\u7684\u534a\u9023\u63a5\u6280\u8853\uff0c\u4e86\u89e3\u5982\u4f55\u5be6\u73fesemi join\u4ee5\u63d0\u9ad8\u67e5\u8a62\u6548\u7387\u548c\u6578\u64da\u8655\u7406\u6027\u80fd\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-186392","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186392","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=186392"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186392\/revisions"}],"predecessor-version":[{"id":186393,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186392\/revisions\/186393"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=186392"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=186392"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=186392"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}