{"id":182668,"date":"2024-11-09T23:52:21","date_gmt":"2024-11-09T15:52:21","guid":{"rendered":"https:\/\/server.hk\/cnblog\/182668\/"},"modified":"2024-11-09T23:52:22","modified_gmt":"2024-11-09T15:52:22","slug":"%e5%af%a6%e4%be%8b%e8%ac%9b%e8%a7%a3mysql%e9%80%a3%e6%8e%a5%e6%9f%a5%e8%a9%a2","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/182668\/","title":{"rendered":"\u5be6\u4f8b\u8b1b\u89e3MySQL\u9023\u63a5\u67e5\u8a62"},"content":{"rendered":"<h1 id=\"%e5%af%a6%e4%be%8b%e8%ac%9b%e8%a7%a3mysql%e9%80%a3%e6%8e%a5%e6%9f%a5%e8%a9%a2-ZsVlzdVHdn\">\u5be6\u4f8b\u8b1b\u89e3MySQL\u9023\u63a5\u67e5\u8a62<\/h1>\n<p>MySQL\u662f\u4e00\u7a2e\u6d41\u884c\u7684\u958b\u6e90\u95dc\u806f\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\uff0c\u5ee3\u6cdb\u61c9\u7528\u65bc\u5404\u7a2e\u61c9\u7528\u7a0b\u5e8f\u4e2d\u3002\u7121\u8ad6\u662f\u5c0f\u578b\u7db2\u7ad9\u9084\u662f\u5927\u578b\u4f01\u696d\u7cfb\u7d71\uff0cMySQL\u90fd\u80fd\u63d0\u4f9b\u9ad8\u6548\u7684\u6578\u64da\u5b58\u5132\u548c\u6aa2\u7d22\u529f\u80fd\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0eMySQL\u7684\u9023\u63a5\u67e5\u8a62\uff0c\u4e26\u901a\u904e\u5be6\u4f8b\u4f86\u5e6b\u52a9\u8b80\u8005\u66f4\u597d\u5730\u7406\u89e3\u5176\u904b\u4f5c\u65b9\u5f0f\u3002<\/p>\n<h2 id=\"mysql%e9%80%a3%e6%8e%a5%e6%9f%a5%e8%a9%a2%e7%9a%84%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-ZsVlzdVHdn\">MySQL\u9023\u63a5\u67e5\u8a62\u7684\u57fa\u672c\u6982\u5ff5<\/h2>\n<p>\u5728MySQL\u4e2d\uff0c\u9023\u63a5\u67e5\u8a62\uff08Join Query\uff09\u662f\u7528\u4f86\u5f9e\u591a\u500b\u8868\u4e2d\u6aa2\u7d22\u6578\u64da\u7684\u4e00\u7a2e\u67e5\u8a62\u65b9\u5f0f\u3002\u901a\u904e\u9023\u63a5\u67e5\u8a62\uff0c\u4f7f\u7528\u8005\u53ef\u4ee5\u6839\u64da\u67d0\u4e9b\u689d\u4ef6\u5c07\u4e0d\u540c\u8868\u4e2d\u7684\u6578\u64da\u7d50\u5408\u8d77\u4f86\u3002MySQL\u652f\u6301\u591a\u7a2e\u9023\u63a5\u985e\u578b\uff0c\u5305\u62ec\u5167\u90e8\u9023\u63a5\uff08INNER JOIN\uff09\u3001\u5916\u90e8\u9023\u63a5\uff08LEFT JOIN\u3001RIGHT JOIN\uff09\u548c\u4ea4\u53c9\u9023\u63a5\uff08CROSS JOIN\uff09\u7b49\u3002<\/p>\n<h2 id=\"%e5%85%a7%e9%83%a8%e9%80%a3%e6%8e%a5%ef%bc%88inner-join%ef%bc%89-ZsVlzdVHdn\">\u5167\u90e8\u9023\u63a5\uff08INNER JOIN\uff09<\/h2>\n<p>\u5167\u90e8\u9023\u63a5\u662f\u6700\u5e38\u7528\u7684\u9023\u63a5\u985e\u578b\uff0c\u5b83\u53ea\u8fd4\u56de\u5728\u5169\u500b\u8868\u4e2d\u90fd\u5b58\u5728\u7684\u8a18\u9304\u3002\u4ee5\u4e0b\u662f\u4e00\u500b\u7c21\u55ae\u7684\u4f8b\u5b50\uff1a<\/p>\n<pre><code>SELECT employees.name, departments.department_name\nFROM employees\nINNER JOIN departments ON employees.department_id = departments.id;<\/code><\/pre>\n<p>\u5728\u9019\u500b\u67e5\u8a62\u4e2d\uff0c\u6211\u5011\u5f9e<code>employees<\/code>\u8868\u548c<code>departments<\/code>\u8868\u4e2d\u9078\u64c7\u54e1\u5de5\u59d3\u540d\u548c\u90e8\u9580\u540d\u7a31\u3002\u9023\u63a5\u689d\u4ef6\u662f<code>employees.department_id<\/code>\u5fc5\u9808\u7b49\u65bc<code>departments.id<\/code>\u3002\u9019\u6a23\uff0c\u6211\u5011\u5c31\u80fd\u7372\u5f97\u6bcf\u4f4d\u54e1\u5de5\u53ca\u5176\u6240\u5c6c\u90e8\u9580\u7684\u5217\u8868\u3002<\/p>\n<h2 id=\"%e5%b7%a6%e5%a4%96%e9%83%a8%e9%80%a3%e6%8e%a5%ef%bc%88left-join%ef%bc%89-ZsVlzdVHdn\">\u5de6\u5916\u90e8\u9023\u63a5\uff08LEFT JOIN\uff09<\/h2>\n<p>\u5de6\u5916\u90e8\u9023\u63a5\u8fd4\u56de\u5de6\u8868\u4e2d\u7684\u6240\u6709\u8a18\u9304\uff0c\u5373\u4f7f\u5728\u53f3\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u8a18\u9304\u3002\u4ee5\u4e0b\u662f\u4f7f\u7528\u5de6\u5916\u90e8\u9023\u63a5\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT employees.name, departments.department_name\nFROM employees\nLEFT JOIN departments ON employees.department_id = departments.id;<\/code><\/pre>\n<p>\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de\u6240\u6709\u54e1\u5de5\u7684\u59d3\u540d\uff0c\u4e26\u4e14\u5982\u679c\u67d0\u4f4d\u54e1\u5de5\u6c92\u6709\u6240\u5c6c\u90e8\u9580\uff0c\u5247<code>department_name<\/code>\u5c07\u986f\u793a\u70baNULL\u3002<\/p>\n<h2 id=\"%e5%8f%b3%e5%a4%96%e9%83%a8%e9%80%a3%e6%8e%a5%ef%bc%88right-join%ef%bc%89-ZsVlzdVHdn\">\u53f3\u5916\u90e8\u9023\u63a5\uff08RIGHT JOIN\uff09<\/h2>\n<p>\u53f3\u5916\u90e8\u9023\u63a5\u8207\u5de6\u5916\u90e8\u9023\u63a5\u76f8\u53cd\uff0c\u5b83\u8fd4\u56de\u53f3\u8868\u4e2d\u7684\u6240\u6709\u8a18\u9304\uff0c\u5373\u4f7f\u5728\u5de6\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u8a18\u9304\u3002\u4ee5\u4e0b\u662f\u53f3\u5916\u90e8\u9023\u63a5\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT employees.name, departments.department_name\nFROM employees\nRIGHT JOIN departments ON employees.department_id = departments.id;<\/code><\/pre>\n<p>\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de\u6240\u6709\u90e8\u9580\u7684\u540d\u7a31\uff0c\u4e26\u4e14\u5982\u679c\u67d0\u500b\u90e8\u9580\u6c92\u6709\u54e1\u5de5\uff0c\u5247<code>name<\/code>\u5c07\u986f\u793a\u70baNULL\u3002<\/p>\n<h2 id=\"%e4%ba%a4%e5%8f%89%e9%80%a3%e6%8e%a5%ef%bc%88cross-join%ef%bc%89-ZsVlzdVHdn\">\u4ea4\u53c9\u9023\u63a5\uff08CROSS JOIN\uff09<\/h2>\n<p>\u4ea4\u53c9\u9023\u63a5\u8fd4\u56de\u5169\u500b\u8868\u7684\u7b1b\u5361\u723e\u7a4d\uff0c\u5373\u6bcf\u500b\u5de6\u8868\u7684\u8a18\u9304\u90fd\u8207\u53f3\u8868\u7684\u6bcf\u500b\u8a18\u9304\u76f8\u7d50\u5408\u3002\u4ee5\u4e0b\u662f\u4ea4\u53c9\u9023\u63a5\u7684\u793a\u4f8b\uff1a<\/p>\n<pre><code>SELECT employees.name, departments.department_name\nFROM employees\nCROSS JOIN departments;<\/code><\/pre>\n<p>\u9019\u500b\u67e5\u8a62\u5c07\u8fd4\u56de\u6240\u6709\u54e1\u5de5\u548c\u6240\u6709\u90e8\u9580\u7684\u7d44\u5408\uff0c\u901a\u5e38\u5728\u5be6\u969b\u61c9\u7528\u4e2d\u4e0d\u5e38\u7528\uff0c\u56e0\u70ba\u7d50\u679c\u96c6\u53ef\u80fd\u6703\u975e\u5e38\u9f90\u5927\u3002<\/p>\n<h2 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