{"id":180886,"date":"2024-11-09T14:00:18","date_gmt":"2024-11-09T06:00:18","guid":{"rendered":"https:\/\/server.hk\/cnblog\/180886\/"},"modified":"2024-11-09T14:00:19","modified_gmt":"2024-11-09T06:00:19","slug":"%e6%b7%b1%e5%85%a5%e4%ba%86%e8%a7%a3%e6%95%b8%e6%93%9a%e5%ba%ab%ef%bc%9a%e4%b8%89%e8%a1%a8%e5%a4%96%e9%80%a3%e6%8e%a5%e8%a9%b3%e8%a7%a3-%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e4%b8%89%e8%a1%a8%e5%a4%96","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/180886\/","title":{"rendered":"\u6df1\u5165\u4e86\u89e3\u6578\u64da\u5eab\uff1a\u4e09\u8868\u5916\u9023\u63a5\u8a73\u89e3 (\u6578\u64da\u5eab\u4e2d\u4e09\u8868\u5916\u9023\u63a5)"},"content":{"rendered":"<h1 id=\"%e6%b7%b1%e5%85%a5%e4%ba%86%e8%a7%a3%e6%95%b8%e6%93%9a%e5%ba%ab%ef%bc%9a%e4%b8%89%e8%a1%a8%e5%a4%96%e9%80%a3%e6%8e%a5%e8%a9%b3%e8%a7%a3-WiYrdeOdrD\">\u6df1\u5165\u4e86\u89e3\u6578\u64da\u5eab\uff1a\u4e09\u8868\u5916\u9023\u63a5\u8a73\u89e3<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0c\u5916\u9023\u63a5\u662f\u4e00\u7a2e\u91cd\u8981\u7684\u67e5\u8a62\u65b9\u5f0f\uff0c\u80fd\u5920\u5f9e\u591a\u500b\u8868\u4e2d\u63d0\u53d6\u76f8\u95dc\u6578\u64da\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e\u4e09\u8868\u5916\u9023\u63a5\u7684\u6982\u5ff5\u3001\u985e\u578b\u53ca\u5176\u5be6\u73fe\u65b9\u6cd5\uff0c\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u9019\u4e00\u6280\u8853\u3002<\/p>\n<h2 id=\"%e5%a4%96%e9%80%a3%e6%8e%a5%e7%9a%84%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-WiYrdeOdrD\">\u5916\u9023\u63a5\u7684\u57fa\u672c\u6982\u5ff5<\/h2>\n<p>\u5916\u9023\u63a5\uff08Outer Join\uff09\u662f\u6307\u5728\u67e5\u8a62\u6642\uff0c\u9664\u4e86\u8fd4\u56de\u7b26\u5408\u689d\u4ef6\u7684\u8a18\u9304\u5916\uff0c\u9084\u6703\u8fd4\u56de\u4e0d\u7b26\u5408\u689d\u4ef6\u7684\u8a18\u9304\u3002\u9019\u4e9b\u4e0d\u7b26\u5408\u689d\u4ef6\u7684\u8a18\u9304\u6703\u4ee5NULL\u503c\u586b\u5145\u3002\u5916\u9023\u63a5\u4e3b\u8981\u5206\u70ba\u4e09\u7a2e\u985e\u578b\uff1a\u5de6\u5916\u9023\u63a5\uff08Left Outer Join\uff09\u3001\u53f3\u5916\u9023\u63a5\uff08Right Outer Join\uff09\u548c\u5168\u5916\u9023\u63a5\uff08Full Outer Join\uff09\u3002<\/p>\n<h2 id=\"%e4%b8%89%e8%a1%a8%e5%a4%96%e9%80%a3%e6%8e%a5%e7%9a%84%e6%a6%82%e5%bf%b5-WiYrdeOdrD\">\u4e09\u8868\u5916\u9023\u63a5\u7684\u6982\u5ff5<\/h2>\n<p>\u4e09\u8868\u5916\u9023\u63a5\u662f\u6307\u5728\u4e00\u500b\u67e5\u8a62\u4e2d\u540c\u6642\u6d89\u53ca\u4e09\u500b\u8868\u7684\u5916\u9023\u63a5\u3002\u9019\u7a2e\u67e5\u8a62\u901a\u5e38\u7528\u65bc\u9700\u8981\u5f9e\u591a\u500b\u8868\u4e2d\u7372\u53d6\u76f8\u95dc\u6578\u64da\u7684\u60c5\u6cc1\u3002\u8209\u4f8b\u4f86\u8aaa\uff0c\u5047\u8a2d\u6211\u5011\u6709\u4e09\u500b\u8868\uff1a<code>Customers<\/code>\uff08\u5ba2\u6236\uff09\u3001<code>Orders<\/code>\uff08\u8a02\u55ae\uff09\u548c<code>Products<\/code>\uff08\u7522\u54c1\uff09\u3002\u6211\u5011\u5e0c\u671b\u7372\u53d6\u6240\u6709\u5ba2\u6236\u7684\u8a02\u55ae\u53ca\u5176\u6240\u8a02\u8cfc\u7684\u7522\u54c1\uff0c\u5373\u4f7f\u67d0\u4e9b\u5ba2\u6236\u6c92\u6709\u8a02\u55ae\u6216\u67d0\u4e9b\u8a02\u55ae\u6c92\u6709\u5c0d\u61c9\u7684\u7522\u54c1\u3002<\/p>\n<h2 id=\"%e4%b8%89%e8%a1%a8%e5%a4%96%e9%80%a3%e6%8e%a5%e7%9a%84%e5%af%a6%e7%8f%be-WiYrdeOdrD\">\u4e09\u8868\u5916\u9023\u63a5\u7684\u5be6\u73fe<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528 SQL \u8a9e\u53e5\u5be6\u73fe\u4e09\u8868\u5916\u9023\u63a5\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>\nSELECT \n    Customers.CustomerID, \n    Customers.CustomerName, \n    Orders.OrderID, \n    Products.ProductName\nFROM \n    Customers\nLEFT OUTER JOIN \n    Orders ON Customers.CustomerID = Orders.CustomerID\nLEFT OUTER JOIN \n    Products ON Orders.ProductID = Products.ProductID;\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6211\u5011\u9996\u5148\u5f9e <code>Customers<\/code> \u8868\u4e2d\u9078\u64c7\u6240\u6709\u5ba2\u6236\uff0c\u7136\u5f8c\u4f7f\u7528\u5de6\u5916\u9023\u63a5\u5c07\u5176\u8207 <code>Orders<\/code> \u8868\u9023\u63a5\uff0c\u63a5\u8457\u518d\u4f7f\u7528\u5de6\u5916\u9023\u63a5\u5c07\u5176\u8207 <code>Products<\/code> \u8868\u9023\u63a5\u3002\u9019\u6a23\uff0c\u5373\u4f7f\u67d0\u4e9b\u5ba2\u6236\u6c92\u6709\u8a02\u55ae\u6216\u67d0\u4e9b\u8a02\u55ae\u6c92\u6709\u5c0d\u61c9\u7684\u7522\u54c1\uff0c\u67e5\u8a62\u7d50\u679c\u4ecd\u7136\u6703\u986f\u793a\u6240\u6709\u5ba2\u6236\u7684\u4fe1\u606f\u3002<\/p>\n<h2 id=\"%e5%a4%96%e9%80%a3%e6%8e%a5%e7%9a%84%e6%87%89%e7%94%a8%e5%a0%b4%e6%99%af-WiYrdeOdrD\">\u5916\u9023\u63a5\u7684\u61c9\u7528\u5834\u666f<\/h2>\n<p>\u4e09\u8868\u5916\u9023\u63a5\u5728\u5be6\u969b\u61c9\u7528\u4e2d\u6709\u591a\u7a2e\u5834\u666f\uff0c\u4f8b\u5982\uff1a<\/p>\n<ul>\n<li><strong>\u5831\u544a\u751f\u6210\uff1a<\/strong>\u5728\u751f\u6210\u5831\u544a\u6642\uff0c\u53ef\u80fd\u9700\u8981\u5f9e\u591a\u500b\u8868\u4e2d\u63d0\u53d6\u6578\u64da\uff0c\u5916\u9023\u63a5\u53ef\u4ee5\u78ba\u4fdd\u5373\u4f7f\u67d0\u4e9b\u6578\u64da\u7f3a\u5931\uff0c\u5831\u544a\u4ecd\u7136\u5b8c\u6574\u3002<\/li>\n<li><strong>\u6578\u64da\u5206\u6790\uff1a<\/strong>\u5728\u9032\u884c\u6578\u64da\u5206\u6790\u6642\uff0c\u5916\u9023\u63a5\u53ef\u4ee5\u5e6b\u52a9\u5206\u6790\u5e2b\u7372\u53d6\u66f4\u5168\u9762\u7684\u6578\u64da\u8996\u5716\uff0c\u5f9e\u800c\u505a\u51fa\u66f4\u6e96\u78ba\u7684\u6c7a\u7b56\u3002<\/li>\n<li><strong>\u6578\u64da\u6574\u5408\uff1a<\/strong>\u5728\u6578\u64da\u6574\u5408\u904e\u7a0b\u4e2d\uff0c\u5916\u9023\u63a5\u53ef\u4ee5\u5e6b\u52a9\u6574\u5408\u4f86\u81ea\u4e0d\u540c\u4f86\u6e90\u7684\u6578\u64da\uff0c\u78ba\u4fdd\u6578\u64da\u7684\u5b8c\u6574\u6027\u3002<\/li>\n<\/ul>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-WiYrdeOdrD\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4f7f\u7528\u4e09\u8868\u5916\u9023\u63a5\u6642\uff0c\u9700\u8981\u6ce8\u610f\u4ee5\u4e0b\u5e7e\u9ede\uff1a<\/p>\n<ul>\n<li><strong>\u6027\u80fd\u554f\u984c\uff1a<\/strong>\u5916\u9023\u63a5\u53ef\u80fd\u6703\u5c0e\u81f4\u67e5\u8a62\u6027\u80fd\u4e0b\u964d\uff0c\u7279\u5225\u662f\u5728\u8655\u7406\u5927\u91cf\u6578\u64da\u6642\u3002\u56e0\u6b64\uff0c\u61c9\u8b39\u614e\u4f7f\u7528\uff0c\u4e26\u8003\u616e\u512a\u5316\u67e5\u8a62\u3002<\/li>\n<li><strong>NULL\u503c\u8655\u7406\uff1a<\/strong>\u67e5\u8a62\u7d50\u679c\u4e2d\u53ef\u80fd\u6703\u51fa\u73feNULL\u503c\uff0c\u9019\u9700\u8981\u5728\u5f8c\u7e8c\u7684\u6578\u64da\u8655\u7406\u4e2d\u9032\u884c\u9069\u7576\u7684\u8655\u7406\u3002<\/li>\n<li><strong>\u6578\u64da\u4e00\u81f4\u6027\uff1a<\/strong>\u78ba\u4fdd\u53c3\u8207\u9023\u63a5\u7684\u8868\u4e4b\u9593\u7684\u6578\u64da\u4e00\u81f4\u6027\uff0c\u4ee5\u907f\u514d\u51fa\u73fe\u4e0d\u6b63\u78ba\u7684\u67e5\u8a62\u7d50\u679c\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-WiYrdeOdrD\">\u7e3d\u7d50<\/h2>\n<p>\u4e09\u8868\u5916\u9023\u63a5\u662f\u4e00\u7a2e\u5f37\u5927\u7684\u6578\u64da\u67e5\u8a62\u6280\u8853\uff0c\u80fd\u5920\u5e6b\u52a9\u7528\u6236\u5f9e\u591a\u500b\u8868\u4e2d\u63d0\u53d6\u76f8\u95dc\u6578\u64da\u3002\u901a\u904e\u5408\u7406\u4f7f\u7528\u5916\u9023\u63a5\uff0c\u6578\u64da\u5206\u6790\u548c\u5831\u544a\u751f\u6210\u7684\u904e\u7a0b\u5c07\u8b8a\u5f97\u66f4\u52a0\u9ad8\u6548\u548c\u5168\u9762\u3002\u5c0d\u65bc\u9700\u8981\u9ad8\u6548\u6578\u64da\u8655\u7406\u7684\u4f01\u696d\uff0c\u9078\u64c7\u5408\u9069\u7684\u6578\u64da\u5eab\u548c\u4f3a\u670d\u5668\u74b0\u5883\u81f3\u95dc\u91cd\u8981\u3002\u82e5\u60a8\u5c0d\u65bc <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u6216\u5176\u4ed6\u4f3a\u670d\u5668\u89e3\u6c7a\u65b9\u6848\u611f\u8208\u8da3\uff0c\u6b61\u8fce\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4ee5\u7372\u53d6\u66f4\u591a\u4fe1\u606f\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6df1\u5165\u4e86\u89e3\u6578\u64da\u5eab\u4e2d\u7684\u4e09\u8868\u5916\u9023\u63a5\uff0c\u638c\u63e1\u5176\u539f\u7406\u8207\u61c9\u7528\uff0c\u63d0\u5347\u6578\u64da\u67e5\u8a62\u6548\u7387\uff0c\u52a9\u529b\u6578\u64da\u5206\u6790\u8207\u7ba1\u7406\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-180886","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/180886","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=180886"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/180886\/revisions"}],"predecessor-version":[{"id":180887,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/180886\/revisions\/180887"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=180886"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=180886"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=180886"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}