{"id":76232,"date":"2024-10-16T04:57:14","date_gmt":"2024-10-15T20:57:14","guid":{"rendered":"https:\/\/server.hk\/cnblog\/76232\/"},"modified":"2024-10-16T04:57:15","modified_gmt":"2024-10-15T20:57:15","slug":"mysql%e5%85%a5%e9%96%80%ef%bc%9a%e4%bd%bf%e7%94%a8join%e9%97%9c%e9%8d%b5%e5%ad%97%e5%9f%ba%e6%96%bc%e7%9b%b8%e9%97%9c%e5%88%97%e5%90%88%e4%bd%b5%e5%85%a9%e5%80%8b%e6%88%96%e5%a4%9a%e5%80%8b%e8%a1%a8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/76232\/","title":{"rendered":"MySQL\u5165\u9580\uff1a\u4f7f\u7528JOIN\u95dc\u9375\u5b57\u57fa\u65bc\u76f8\u95dc\u5217\u5408\u4f75\u5169\u500b\u6216\u591a\u500b\u8868\u4e2d\u7684\u884c\u3002"},"content":{"rendered":"<h1 id=\"mysql%e5%85%a5%e9%96%80%ef%bc%9a%e4%bd%bf%e7%94%a8join%e9%97%9c%e9%8d%b5%e5%ad%97%e5%9f%ba%e6%96%bc%e7%9b%b8%e9%97%9c%e5%88%97%e5%90%88%e4%bd%b5%e5%85%a9%e5%80%8b%e6%88%96%e5%a4%9a%e5%80%8b%e8%a1%a8-YAohwlHHiJ\">MySQL\u5165\u9580\uff1a\u4f7f\u7528JOIN\u95dc\u9375\u5b57\u57fa\u65bc\u76f8\u95dc\u5217\u5408\u4f75\u5169\u500b\u6216\u591a\u500b\u8868\u4e2d\u7684\u884c<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cMySQL\u662f\u4e00\u500b\u5ee3\u6cdb\u4f7f\u7528\u7684\u958b\u6e90\u95dc\u806f\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u3002\u5b83\u7684\u5f37\u5927\u529f\u80fd\u4f7f\u5f97\u7528\u6236\u80fd\u5920\u9ad8\u6548\u5730\u5b58\u5132\u3001\u6aa2\u7d22\u548c\u7ba1\u7406\u6578\u64da\u3002\u7576\u6d89\u53ca\u5230\u591a\u500b\u8868\u7684\u6578\u64da\u6642\uff0cJOIN\u95dc\u9375\u5b57\u662f\u975e\u5e38\u91cd\u8981\u7684\u5de5\u5177\uff0c\u80fd\u5920\u6839\u64da\u76f8\u95dc\u5217\u5408\u4f75\u5169\u500b\u6216\u591a\u500b\u8868\u4e2d\u7684\u884c\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0eJOIN\u7684\u985e\u578b\u53ca\u5176\u7528\u6cd5\uff0c\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u5982\u4f55\u5728MySQL\u4e2d\u4f7f\u7528JOIN\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%afjoin%ef%bc%9f-YAohwlHHiJ\">\u4ec0\u9ebc\u662fJOIN\uff1f<\/h2>\n<p>JOIN\u662f\u4e00\u7a2eSQL\u64cd\u4f5c\uff0c\u7528\u65bc\u6839\u64da\u4e00\u500b\u6216\u591a\u500b\u5171\u540c\u7684\u5217\u5c07\u5169\u500b\u6216\u591a\u500b\u8868\u4e2d\u7684\u6578\u64da\u5408\u4f75\u3002\u9019\u4f7f\u5f97\u7528\u6236\u80fd\u5920\u5f9e\u4e0d\u540c\u7684\u8868\u4e2d\u63d0\u53d6\u76f8\u95dc\u6578\u64da\uff0c\u5f9e\u800c\u9032\u884c\u66f4\u8907\u96dc\u7684\u67e5\u8a62\u3002<\/p>\n<h2 id=\"join%e7%9a%84%e9%a1%9e%e5%9e%8b-YAohwlHHiJ\">JOIN\u7684\u985e\u578b<\/h2>\n<p>MySQL\u4e2d\u6709\u5e7e\u7a2e\u4e3b\u8981\u7684JOIN\u985e\u578b\uff0c\u6bcf\u7a2e\u90fd\u6709\u5176\u7279\u5b9a\u7684\u7528\u9014\uff1a<\/p>\n<ul>\n<li><strong>INNER JOIN<\/strong>: \u53ea\u8fd4\u56de\u5169\u500b\u8868\u4e2d\u5339\u914d\u7684\u884c\u3002\u5982\u679c\u67d0\u4e00\u8868\u4e2d\u7684\u884c\u5728\u53e6\u4e00\u8868\u4e2d\u6c92\u6709\u5339\u914d\uff0c\u5247\u8a72\u884c\u4e0d\u6703\u51fa\u73fe\u5728\u7d50\u679c\u4e2d\u3002<\/li>\n<li><strong>LEFT JOIN (\u6216 LEFT OUTER JOIN)<\/strong>: \u8fd4\u56de\u5de6\u5074\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u5728\u53f3\u5074\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\u3002\u5982\u679c\u53f3\u5074\u8868\u4e2d\u6c92\u6709\u5339\u914d\uff0c\u5247\u7d50\u679c\u4e2d\u8a72\u884c\u7684\u6240\u6709\u5217\u5c07\u986f\u793a\u70baNULL\u3002<\/li>\n<li><strong>RIGHT JOIN (\u6216 RIGHT OUTER JOIN)<\/strong>: \u8207LEFT JOIN\u76f8\u53cd\uff0c\u8fd4\u56de\u53f3\u5074\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u5728\u5de6\u5074\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\u3002<\/li>\n<li><strong>FULL JOIN (\u6216 FULL OUTER JOIN)<\/strong>: \u8fd4\u56de\u5169\u500b\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u7121\u8ad6\u662f\u5426\u6709\u5339\u914d\u7684\u884c\u3002\u5982\u679c\u67d0\u4e00\u8868\u4e2d\u6c92\u6709\u5339\u914d\uff0c\u5247\u8a72\u884c\u7684\u6240\u6709\u5217\u5c07\u986f\u793a\u70baNULL\u3002<\/li>\n<li><strong>CROSS JOIN<\/strong>: \u8fd4\u56de\u5169\u500b\u8868\u7684\u7b1b\u5361\u723e\u7a4d\uff0c\u5373\u6bcf\u4e00\u884c\u8207\u53e6\u4e00\u8868\u4e2d\u7684\u6bcf\u4e00\u884c\u90fd\u6703\u7d44\u5408\u3002<\/li>\n<\/ul>\n<h2 id=\"%e4%bd%bf%e7%94%a8join%e7%9a%84%e7%af%84%e4%be%8b-YAohwlHHiJ\">\u4f7f\u7528JOIN\u7684\u7bc4\u4f8b<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528INNER JOIN\u7684\u7bc4\u4f8b\uff0c\u5047\u8a2d\u6211\u5011\u6709\u5169\u500b\u8868\uff1a<code>customers<\/code>\u548c<code>orders<\/code>\u3002<\/p>\n<pre><code>SELECT customers.name, orders.order_date\nFROM customers\nINNER JOIN orders ON customers.id = orders.customer_id;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6211\u5011\u5f9e<code>customers<\/code>\u8868\u4e2d\u9078\u64c7\u5ba2\u6236\u7684\u540d\u5b57\uff0c\u4e26\u5f9e<code>orders<\/code>\u8868\u4e2d\u9078\u64c7\u8a02\u55ae\u65e5\u671f\u3002\u9019\u88e1\u7684JOIN\u64cd\u4f5c\u662f\u57fa\u65bc<code>customers<\/code>\u8868\u7684<code>id<\/code>\u5217\u548c<code>orders<\/code>\u8868\u7684<code>customer_id<\/code>\u5217\u9032\u884c\u7684\u3002<\/p>\n<h2 id=\"left-join%e7%9a%84%e7%af%84%e4%be%8b-YAohwlHHiJ\">LEFT JOIN\u7684\u7bc4\u4f8b<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528LEFT JOIN\u7684\u7bc4\u4f8b\uff1a<\/p>\n<pre><code>SELECT customers.name, orders.order_date\nFROM customers\nLEFT JOIN orders ON customers.id = orders.customer_id;<\/code><\/pre>\n<p>\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de\u6240\u6709\u5ba2\u6236\u7684\u540d\u5b57\uff0c\u5373\u4f7f\u4ed6\u5011\u6c92\u6709\u4efb\u4f55\u8a02\u55ae\u3002\u5728\u9019\u7a2e\u60c5\u6cc1\u4e0b\uff0c\u5c0d\u65bc\u6c92\u6709\u8a02\u55ae\u7684\u5ba2\u6236\uff0c<code>order_date<\/code>\u5c07\u986f\u793a\u70baNULL\u3002<\/p>\n<h2 id=\"%e7%b5%90%e8%ab%96-YAohwlHHiJ\">\u7d50\u8ad6<\/h2>\n<p>\u4f7f\u7528JOIN\u95dc\u9375\u5b57\u53ef\u4ee5\u6709\u6548\u5730\u5408\u4f75\u591a\u500b\u8868\u4e2d\u7684\u6578\u64da\uff0c\u9019\u5c0d\u65bc\u9032\u884c\u8907\u96dc\u67e5\u8a62\u548c\u6578\u64da\u5206\u6790\u81f3\u95dc\u91cd\u8981\u3002\u7121\u8ad6\u662fINNER JOIN\u3001LEFT 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