{"id":186800,"date":"2024-11-11T08:56:25","date_gmt":"2024-11-11T00:56:25","guid":{"rendered":"https:\/\/server.hk\/cnblog\/186800\/"},"modified":"2024-11-11T08:56:26","modified_gmt":"2024-11-11T00:56:26","slug":"%e6%95%b8%e6%93%9a%e5%ba%ab%e9%96%8b%e7%99%bc%e6%87%89%e7%9f%a5%e6%87%89%e6%9c%83%e4%b9%8b%e7%ac%9b%e5%8d%a1%e7%88%be%e7%a9%8d","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/186800\/","title":{"rendered":"\u6578\u64da\u5eab\u958b\u767c\u61c9\u77e5\u61c9\u6703\u4e4b\u7b1b\u5361\u723e\u7a4d"},"content":{"rendered":"<h1 id=\"%e6%95%b8%e6%93%9a%e5%ba%ab%e9%96%8b%e7%99%bc%e6%87%89%e7%9f%a5%e6%87%89%e6%9c%83%e4%b9%8b%e7%ac%9b%e5%8d%a1%e7%88%be%e7%a9%8d-CyIxHFehOa\">\u6578\u64da\u5eab\u958b\u767c\u61c9\u77e5\u61c9\u6703\u4e4b\u7b1b\u5361\u723e\u7a4d<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u958b\u767c\u4e2d\uff0c\u7406\u89e3\u548c\u904b\u7528\u7b1b\u5361\u723e\u7a4d\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002\u7b1b\u5361\u723e\u7a4d\uff08Cartesian Product\uff09\u662f\u6578\u5b78\u4e2d\u4e00\u500b\u57fa\u672c\u7684\u6982\u5ff5\uff0c\u5c24\u5176\u5728\u95dc\u806f\u6578\u64da\u5eab\u4e2d\uff0c\u5b83\u7528\u65bc\u63cf\u8ff0\u5169\u500b\u6216\u591a\u500b\u96c6\u5408\u4e4b\u9593\u7684\u6240\u6709\u53ef\u80fd\u7d44\u5408\u3002\u5728\u9019\u7bc7\u6587\u7ae0\u4e2d\uff0c\u6211\u5011\u5c07\u6df1\u5165\u63a2\u8a0e\u7b1b\u5361\u723e\u7a4d\u7684\u5b9a\u7fa9\u3001\u904b\u7528\u53ca\u5176\u5728\u6578\u64da\u5eab\u67e5\u8a62\u4e2d\u7684\u91cd\u8981\u6027\u3002<\/p>\n<h2 id=\"%e7%ac%9b%e5%8d%a1%e7%88%be%e7%a9%8d%e7%9a%84%e5%ae%9a%e7%be%a9-CyIxHFehOa\">\u7b1b\u5361\u723e\u7a4d\u7684\u5b9a\u7fa9<\/h2>\n<p>\u7b1b\u5361\u723e\u7a4d\u662f\u6307\u5169\u500b\u96c6\u5408\u4e2d\u6240\u6709\u5143\u7d20\u7684\u7d44\u5408\u3002\u5047\u8a2d\u6709\u5169\u500b\u96c6\u5408 A \u548c B\uff0c\u5247 A \u548c B \u7684\u7b1b\u5361\u723e\u7a4d\u8a18\u4f5c A \u00d7 B\uff0c\u5b9a\u7fa9\u70ba\uff1a<\/p>\n<pre><code>\nA \u00d7 B = {(a, b) | a \u2208 A, b \u2208 B}\n<\/code><\/pre>\n<p>\u9019\u610f\u5473\u8457\uff0c\u7b1b\u5361\u723e\u7a4d\u6703\u751f\u6210\u4e00\u500b\u65b0\u7684\u96c6\u5408\uff0c\u5176\u4e2d\u5305\u542b\u6240\u6709\u53ef\u80fd\u7684\u6709\u5e8f\u5c0d (a, b)\uff0c\u5176\u4e2d a \u4f86\u81ea\u96c6\u5408 A\uff0cb \u4f86\u81ea\u96c6\u5408 B\u3002<\/p>\n<h2 id=\"%e5%9c%a8%e6%95%b8%e6%93%9a%e5%ba%ab%e4%b8%ad%e7%9a%84%e6%87%89%e7%94%a8-CyIxHFehOa\">\u5728\u6578\u64da\u5eab\u4e2d\u7684\u61c9\u7528<\/h2>\n<p>\u5728\u95dc\u806f\u6578\u64da\u5eab\u4e2d\uff0c\u7b1b\u5361\u723e\u7a4d\u901a\u5e38\u662f\u901a\u904e SQL \u67e5\u8a62\u4e2d\u7684 JOIN \u64cd\u4f5c\u4f86\u5be6\u73fe\u7684\u3002\u7576\u6211\u5011\u5c0d\u5169\u500b\u6216\u591a\u500b\u8868\u9032\u884c JOIN \u6642\uff0c\u6578\u64da\u5eab\u7cfb\u7d71\u6703\u81ea\u52d5\u8a08\u7b97\u9019\u4e9b\u8868\u7684\u7b1b\u5361\u723e\u7a4d\uff0c\u7136\u5f8c\u6839\u64da\u6307\u5b9a\u7684\u689d\u4ef6\u904e\u6ffe\u51fa\u6240\u9700\u7684\u7d50\u679c\u3002<\/p>\n<h3 id=\"%e7%a4%ba%e4%be%8b%ef%bc%9a%e4%bd%bf%e7%94%a8-sql-%e9%80%b2%e8%a1%8c%e7%ac%9b%e5%8d%a1%e7%88%be%e7%a9%8d-CyIxHFehOa\">\u793a\u4f8b\uff1a\u4f7f\u7528 SQL \u9032\u884c\u7b1b\u5361\u723e\u7a4d<\/h3>\n<p>\u5047\u8a2d\u6211\u5011\u6709\u5169\u500b\u8868\uff1a<strong>Customers<\/strong> \u548c <strong>Orders<\/strong>\u3002<\/p>\n<pre><code>\nCustomers:\n+----+----------+\n| ID | Name     |\n+----+----------+\n| 1  | Alice    |\n| 2  | Bob      |\n+----+----------+\n\nOrders:\n+----+------------+\n| ID | CustomerID |\n+----+------------+\n| 1  | 1          |\n| 2  | 2          |\n| 3  | 1          |\n+----+------------+\n<\/code><\/pre>\n<p>\u5982\u679c\u6211\u5011\u57f7\u884c\u4ee5\u4e0b SQL \u67e5\u8a62\uff1a<\/p>\n<pre><code>\nSELECT * FROM Customers, Orders;\n<\/code><\/pre>\n<p>\u9019\u5c07\u7522\u751f Customers \u548c Orders \u8868\u7684\u7b1b\u5361\u723e\u7a4d\uff0c\u7d50\u679c\u5982\u4e0b\uff1a<\/p>\n<pre><code>\n+----+----------+----+------------+\n| ID | Name     | ID | CustomerID |\n+----+----------+----+------------+\n| 1  | Alice    | 1  | 1          |\n| 1  | Alice    | 2  | 2          |\n| 1  | Alice    | 3  | 1          |\n| 2  | Bob      | 1  | 1          |\n| 2  | Bob      | 2  | 2          |\n| 2  | Bob      | 3  | 1          |\n+----+----------+----+------------+\n<\/code><\/pre>\n<p>\u5982\u4e0a\u6240\u793a\uff0c\u7d50\u679c\u96c6\u5305\u542b\u4e86 Customers \u8868\u548c Orders \u8868\u4e2d\u6240\u6709\u53ef\u80fd\u7684\u7d44\u5408\u3002\u9019\u6a23\u7684\u7d50\u679c\u5728\u5be6\u969b\u61c9\u7528\u4e2d\u5f80\u5f80\u662f\u5197\u9918\u7684\uff0c\u56e0\u6b64\u901a\u5e38\u6703\u4f7f\u7528 JOIN \u689d\u4ef6\u4f86\u904e\u6ffe\u7d50\u679c\u3002<\/p>\n<h2 id=\"%e7%ac%9b%e5%8d%a1%e7%88%be%e7%a9%8d%e7%9a%84%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-CyIxHFehOa\">\u7b1b\u5361\u723e\u7a4d\u7684\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u5be6\u969b\u7684\u6578\u64da\u5eab\u958b\u767c\u4e2d\uff0c\u7b1b\u5361\u723e\u7a4d\u53ef\u80fd\u6703\u5c0e\u81f4\u6027\u80fd\u554f\u984c\uff0c\u7279\u5225\u662f\u7576\u6d89\u53ca\u5230\u5927\u578b\u8868\u6642\u3002\u751f\u6210\u7684\u7d50\u679c\u96c6\u53ef\u80fd\u6703\u975e\u5e38\u9f90\u5927\uff0c\u5f9e\u800c\u5f71\u97ff\u67e5\u8a62\u7684\u6548\u7387\u3002\u56e0\u6b64\uff0c\u958b\u767c\u8005\u61c9\u8a72\u8b39\u614e\u4f7f\u7528\u7b1b\u5361\u723e\u7a4d\uff0c\u4e26\u78ba\u4fdd\u5728\u67e5\u8a62\u4e2d\u4f7f\u7528\u9069\u7576\u7684 JOIN \u689d\u4ef6\u4f86\u9650\u5236\u7d50\u679c\u96c6\u7684\u5927\u5c0f\u3002<\/p>\n<h2 id=\"%e7%b8%bd%e7%b5%90-CyIxHFehOa\">\u7e3d\u7d50<\/h2>\n<p>\u7b1b\u5361\u723e\u7a4d\u662f\u6578\u64da\u5eab\u958b\u767c\u4e2d\u4e00\u500b\u57fa\u672c\u800c\u91cd\u8981\u7684\u6982\u5ff5\uff0c\u7406\u89e3\u5176\u904b\u4f5c\u65b9\u5f0f\u5c0d\u65bc\u6709\u6548\u5730\u9032\u884c\u6578\u64da\u67e5\u8a62\u81f3\u95dc\u91cd\u8981\u3002\u901a\u904e\u6b63\u78ba\u4f7f\u7528 SQL \u4e2d\u7684 JOIN \u64cd\u4f5c\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u6709\u6548\u5730\u7ba1\u7406\u548c\u67e5\u8a62\u6578\u64da\uff0c\u5f9e\u800c\u63d0\u9ad8\u61c9\u7528\u7a0b\u5e8f\u7684\u6027\u80fd\u548c\u53ef\u7528\u6027\u3002\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u9ad8\u6548\u7684 <a href=\"https:\/\/server.hk\">VPS<\/a> \u89e3\u6c7a\u65b9\u6848\u4f86\u652f\u6301\u60a8\u7684\u6578\u64da\u5eab\u958b\u767c\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\u4ee5\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3\u6578\u64da\u5eab\u958b\u767c\u4e2d\u7684\u7b1b\u5361\u723e\u7a4d\u6982\u5ff5\uff0c\u638c\u63e1\u5176\u61c9\u7528\u8207\u5f71\u97ff\uff0c\u63d0\u5347\u6578\u64da\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-186800","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186800","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=186800"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186800\/revisions"}],"predecessor-version":[{"id":186801,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/186800\/revisions\/186801"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=186800"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=186800"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=186800"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}