{"id":181296,"date":"2024-11-09T15:52:18","date_gmt":"2024-11-09T07:52:18","guid":{"rendered":"https:\/\/server.hk\/cnblog\/181296\/"},"modified":"2024-11-09T15:52:19","modified_gmt":"2024-11-09T07:52:19","slug":"%e6%b7%b1%e5%85%a5%e7%90%86%e8%a7%a3%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e7%9a%84xy%ef%bc%88%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%adxy%ef%bc%89","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/181296\/","title":{"rendered":"\u6df1\u5165\u7406\u89e3\u6578\u64da\u5eab\u4e2d\u7684xy\uff08\u6578\u64da\u5eab\u4e2dx$y\uff09"},"content":{"rendered":"<h1 id=\"%e6%b7%b1%e5%85%a5%e7%90%86%e8%a7%a3%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e7%9a%84xy%ef%bc%88%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%adxy%ef%bc%89-dtooLkIulq\">\u6df1\u5165\u7406\u89e3\u6578\u64da\u5eab\u4e2d\u7684xy\uff08\u6578\u64da\u5eab\u4e2dx$y\uff09<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0c\u7406\u89e3\u6578\u64da\u7684\u7d50\u69cb\u548c\u5b58\u53d6\u65b9\u5f0f\u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002\u7279\u5225\u662f\u5728\u95dc\u806f\u6578\u64da\u5eab\u4e2d\uff0c\u6578\u64da\u7684\u7d44\u7e54\u548c\u67e5\u8a62\u65b9\u5f0f\u76f4\u63a5\u5f71\u97ff\u5230\u7cfb\u7d71\u7684\u6027\u80fd\u548c\u53ef\u64f4\u5c55\u6027\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e\u6578\u64da\u5eab\u4e2d\u7684xy\uff08\u6578\u64da\u5eab\u4e2dx$y\uff09\u6982\u5ff5\uff0c\u4e26\u63d0\u4f9b\u76f8\u95dc\u7684\u793a\u4f8b\u548c\u4ee3\u78bc\u7247\u6bb5\uff0c\u4ee5\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u9019\u4e00\u4e3b\u984c\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%afxy%ef%bc%88xy%ef%bc%89-dtooLkIulq\">\u4ec0\u9ebc\u662fxy\uff08x$y\uff09<\/h2>\n<p>\u5728\u6578\u64da\u5eab\u4e2d\uff0cxy\uff08\u6216x$y\uff09\u901a\u5e38\u6307\u7684\u662f\u4e00\u7a2e\u7279\u5b9a\u7684\u6578\u64da\u7d50\u69cb\u6216\u67e5\u8a62\u65b9\u5f0f\uff0c\u5176\u4e2dx\u548cy\u4ee3\u8868\u4e0d\u540c\u7684\u6578\u64da\u5143\u7d20\u6216\u8868\u683c\u3002\u9019\u7a2e\u8868\u793a\u6cd5\u5e38\u898b\u65bcSQL\u67e5\u8a62\u4e2d\uff0c\u7279\u5225\u662f\u5728\u6d89\u53ca\u5230\u591a\u500b\u8868\u683c\u7684\u806f\u63a5\u64cd\u4f5c\u6642\u3002\u901a\u904e\u9019\u7a2e\u65b9\u5f0f\uff0c\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u80fd\u5920\u6709\u6548\u5730\u5f9e\u4e0d\u540c\u7684\u6578\u64da\u6e90\u4e2d\u63d0\u53d6\u548c\u7d44\u5408\u6578\u64da\u3002<\/p>\n<h2 id=\"%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e7%9a%84%e8%81%af%e6%8e%a5%e6%93%8d%e4%bd%9c-dtooLkIulq\">\u6578\u64da\u5eab\u4e2d\u7684\u806f\u63a5\u64cd\u4f5c<\/h2>\n<p>\u5728\u95dc\u806f\u6578\u64da\u5eab\u4e2d\uff0c\u806f\u63a5\u64cd\u4f5c\u662f\u5c07\u5169\u500b\u6216\u591a\u500b\u8868\u683c\u4e2d\u7684\u6578\u64da\u6839\u64da\u67d0\u4e9b\u689d\u4ef6\u9032\u884c\u7d44\u5408\u7684\u904e\u7a0b\u3002\u9019\u4e9b\u689d\u4ef6\u901a\u5e38\u662f\u57fa\u65bc\u8868\u683c\u4e2d\u7684\u5171\u540c\u5b57\u6bb5\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u806f\u63a5\u985e\u578b\uff1a<\/p>\n<ul>\n<li><strong>\u5167\u806f\u63a5\uff08INNER JOIN\uff09<\/strong>: \u53ea\u8fd4\u56de\u5169\u500b\u8868\u4e2d\u5339\u914d\u7684\u884c\u3002<\/li>\n<li><strong>\u5916\u806f\u63a5\uff08OUTER JOIN\uff09<\/strong>: \u8fd4\u56de\u81f3\u5c11\u4e00\u500b\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u6c92\u6709\u5339\u914d\u7684\u884c\u3002<\/li>\n<li><strong>\u4ea4\u53c9\u806f\u63a5\uff08CROSS JOIN\uff09<\/strong>: \u8fd4\u56de\u5169\u500b\u8868\u7684\u7b1b\u5361\u723e\u7a4d\u3002<\/li>\n<\/ul>\n<h3 id=\"%e5%85%a7%e8%81%af%e6%8e%a5%e7%a4%ba%e4%be%8b-dtooLkIulq\">\u5167\u806f\u63a5\u793a\u4f8b<\/h3>\n<pre><code>SELECT a.name, b.salary\nFROM employees a\nINNER JOIN salaries b ON a.id = b.employee_id;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0c<code>employees<\/code> \u8868\u548c <code>salaries<\/code> \u8868\u901a\u904e <code>employee_id<\/code> \u9032\u884c\u5167\u806f\u63a5\uff0c\u8fd4\u56de\u6240\u6709\u54e1\u5de5\u7684\u59d3\u540d\u53ca\u5176\u5c0d\u61c9\u7684\u85aa\u6c34\u3002<\/p>\n<h2 id=\"%e4%bd%bf%e7%94%a8xy%ef%bc%88xy%ef%bc%89%e9%80%b2%e8%a1%8c%e6%95%b8%e6%93%9a%e6%9f%a5%e8%a9%a2-dtooLkIulq\">\u4f7f\u7528xy\uff08x$y\uff09\u9032\u884c\u6578\u64da\u67e5\u8a62<\/h2>\n<p>\u5728\u67d0\u4e9b\u60c5\u6cc1\u4e0b\uff0cxy\uff08x$y\uff09\u53ef\u4ee5\u7528\u4f86\u8868\u793a\u7279\u5b9a\u7684\u6578\u64da\u67e5\u8a62\u9700\u6c42\u3002\u4f8b\u5982\uff0c\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b <code>products<\/code> \u8868\u548c\u4e00\u500b <code>categories<\/code> \u8868\uff0c\u6211\u5011\u5e0c\u671b\u67e5\u8a62\u6bcf\u500b\u7522\u54c1\u53ca\u5176\u6240\u5c6c\u985e\u5225\u7684\u540d\u7a31\u3002\u9019\u53ef\u4ee5\u901a\u904e\u4ee5\u4e0bSQL\u67e5\u8a62\u5be6\u73fe\uff1a<\/p>\n<pre><code>SELECT p.product_name, c.category_name\nFROM products p\nJOIN categories c ON p.category_id = c.id;<\/code><\/pre>\n<p>\u9019\u88e1\uff0c<code>p.product_name<\/code> \u548c <code>c.category_name<\/code> \u4ee3\u8868\u4e86xy\uff08x$y\uff09\u4e2d\u7684x\u548cy\uff0c\u5206\u5225\u662f\u7522\u54c1\u540d\u7a31\u548c\u985e\u5225\u540d\u7a31\u3002<\/p>\n<h2 id=\"%e6%80%a7%e8%83%bd%e8%80%83%e9%87%8f-dtooLkIulq\">\u6027\u80fd\u8003\u91cf<\/h2>\n<p>\u5728\u8a2d\u8a08\u6578\u64da\u5eab\u67e5\u8a62\u6642\uff0c\u6027\u80fd\u662f\u4e00\u500b\u91cd\u8981\u7684\u8003\u91cf\u56e0\u7d20\u3002\u4f7f\u7528xy\uff08x$y\uff09\u9032\u884c\u67e5\u8a62\u6642\uff0c\u61c9\u6ce8\u610f\u4ee5\u4e0b\u5e7e\u9ede\uff1a<\/p>\n<ul>\n<li>\u78ba\u4fdd\u9069\u7576\u7684\u7d22\u5f15\uff1a\u70ba\u5e38\u7528\u7684\u67e5\u8a62\u5b57\u6bb5\u5efa\u7acb\u7d22\u5f15\u53ef\u4ee5\u986f\u8457\u63d0\u9ad8\u67e5\u8a62\u6027\u80fd\u3002<\/li>\n<li>\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u806f\u63a5\uff1a\u904e\u591a\u7684\u806f\u63a5\u6703\u5c0e\u81f4\u67e5\u8a62\u8b8a\u6162\uff0c\u61c9\u6839\u64da\u5be6\u969b\u9700\u6c42\u9032\u884c\u512a\u5316\u3002<\/li>\n<li>\u4f7f\u7528\u67e5\u8a62\u8a08\u5283\uff1a\u901a\u904e\u5206\u6790\u67e5\u8a62\u8a08\u5283\uff0c\u53ef\u4ee5\u4e86\u89e3\u67e5\u8a62\u7684\u57f7\u884c\u65b9\u5f0f\uff0c\u4e26\u9032\u884c\u76f8\u61c9\u7684\u8abf\u6574\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b5%90%e8%ab%96-dtooLkIulq\">\u7d50\u8ad6<\/h2>\n<p>\u6df1\u5165\u7406\u89e3\u6578\u64da\u5eab\u4e2d\u7684xy\uff08\u6578\u64da\u5eab\u4e2dx$y\uff09\u6982\u5ff5\u5c0d\u65bc\u6578\u64da\u5eab\u7ba1\u7406\u548c\u6027\u80fd\u512a\u5316\u81f3\u95dc\u91cd\u8981\u3002\u901a\u904e\u5408\u7406\u7684\u6578\u64da\u7d50\u69cb\u8a2d\u8a08\u548c\u67e5\u8a62\u512a\u5316\uff0c\u53ef\u4ee5\u6709\u6548\u63d0\u5347\u7cfb\u7d71\u7684\u6027\u80fd\u548c\u53ef\u64f4\u5c55\u6027\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u8655\u7406\u7684\u61c9\u7528\uff0c\u9078\u64c7\u5408\u9069\u7684\u6578\u64da\u5eab\u89e3\u6c7a\u65b9\u6848\u4e5f\u662f\u4e00\u500b\u91cd\u8981\u7684\u8003\u91cf\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\u4ee5\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002\u7121\u8ad6\u662f\u6578\u64da\u5eab\u7ba1\u7406\u9084\u662f\u5176\u4ed6\u61c9\u7528\uff0c\u6211\u5011\u7684\u670d\u52d9\u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6df1\u5165\u7406\u89e3\u6578\u64da\u5eab\u4e2d\u7684xy\uff08\u6578\u64da\u5eab\u4e2dx$y\uff09\uff0c\u63a2\u7d22\u5176\u7d50\u69cb\u3001\u529f\u80fd\u53ca\u61c9\u7528\uff0c\u63d0\u5347\u6578\u64da\u7ba1\u7406\u8207\u67e5\u8a62\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-181296","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/181296","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=181296"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/181296\/revisions"}],"predecessor-version":[{"id":181297,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/181296\/revisions\/181297"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=181296"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=181296"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=181296"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}