{"id":78840,"date":"2024-10-16T12:22:16","date_gmt":"2024-10-16T04:22:16","guid":{"rendered":"https:\/\/server.hk\/cnblog\/78840\/"},"modified":"2024-10-16T12:22:16","modified_gmt":"2024-10-16T04:22:16","slug":"mysql%e6%8c%87%e4%bb%a4-join%ef%bc%88%e9%80%a3%e6%8e%a5%e8%a1%a8%ef%bc%89","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/78840\/","title":{"rendered":"MySQL\u6307\u4ee4: JOIN\uff08\u9023\u63a5\u8868\uff09"},"content":{"rendered":"<h1 id=\"mysql%e6%8c%87%e4%bb%a4-join%ef%bc%88%e9%80%a3%e6%8e%a5%e8%a1%a8%ef%bc%89-TuhXwEVGDe\">MySQL\u6307\u4ee4: JOIN\uff08\u9023\u63a5\u8868\uff09<\/h1>\n<p>\u5728\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cMySQL\u662f\u4e00\u500b\u5ee3\u6cdb\u4f7f\u7528\u7684\u95dc\u806f\u5f0f\u8cc7\u6599\u5eab\u7ba1\u7406\u7cfb\u7d71\u3002\u7576\u6211\u5011\u9700\u8981\u5f9e\u591a\u500b\u8868\u4e2d\u6aa2\u7d22\u8cc7\u6599\u6642\uff0cJOIN\u6307\u4ee4\u4fbf\u6210\u70ba\u4e86\u4e00\u500b\u4e0d\u53ef\u6216\u7f3a\u7684\u5de5\u5177\u3002JOIN\u6307\u4ee4\u5141\u8a31\u6211\u5011\u6839\u64da\u67d0\u4e9b\u689d\u4ef6\u5c07\u5169\u500b\u6216\u591a\u500b\u8868\u7684\u8cc7\u6599\u7d50\u5408\u5728\u4e00\u8d77\uff0c\u5f9e\u800c\u7372\u5f97\u66f4\u70ba\u8c50\u5bcc\u7684\u8cc7\u8a0a\u3002<\/p>\n<h2 id=\"join%e7%9a%84%e9%a1%9e%e5%9e%8b-TuhXwEVGDe\">JOIN\u7684\u985e\u578b<\/h2>\n<p>MySQL\u4e2d\u6709\u5e7e\u7a2e\u4e3b\u8981\u7684JOIN\u985e\u578b\uff0c\u6bcf\u7a2eJOIN\u90fd\u6709\u5176\u7279\u5b9a\u7684\u7528\u9014\u548c\u7279\u9ede\uff1a<\/p>\n<ul>\n<li><strong>INNER JOIN<\/strong>: \u9019\u662f\u6700\u5e38\u7528\u7684JOIN\u985e\u578b\u3002\u5b83\u53ea\u8fd4\u56de\u5169\u500b\u8868\u4e2d\u5339\u914d\u7684\u884c\u3002\u5982\u679c\u67d0\u4e00\u884c\u5728\u4efb\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\uff08\u6216LEFT OUTER JOIN\uff09<\/strong>: \u6b64JOIN\u8fd4\u56de\u5de6\u5074\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\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\u53f3\u5074\u8868\u7684\u6b04\u4f4d\u5c07\u986f\u793a\u70baNULL\u3002<\/li>\n<li><strong>RIGHT JOIN\uff08\u6216RIGHT OUTER JOIN\uff09<\/strong>: \u8207LEFT JOIN\u76f8\u53cd\uff0cRIGHT JOIN\u8fd4\u56de\u53f3\u5074\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5373\u4f7f\u5de6\u5074\u8868\u4e2d\u6c92\u6709\u5339\u914d\u7684\u884c\u3002<\/li>\n<li><strong>FULL JOIN\uff08\u6216FULL OUTER JOIN\uff09<\/strong>: \u6b64JOIN\u8fd4\u56de\u5169\u500b\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u7121\u8ad6\u662f\u5426\u6709\u5339\u914d\u3002\u5982\u679c\u67d0\u4e00\u884c\u5728\u4efb\u4e00\u8868\u4e2d\u6c92\u6709\u5339\u914d\uff0c\u5247\u8a72\u884c\u7684\u6240\u6709\u6b04\u4f4d\u5c07\u986f\u793a\u70baNULL\u3002<\/li>\n<li><strong>CROSS JOIN<\/strong>: \u6b64JOIN\u8fd4\u56de\u5169\u500b\u8868\u7684\u7b1b\u5361\u723e\u7a4d\uff0c\u5373\u6bcf\u4e00\u884c\u90fd\u8207\u53e6\u4e00\u8868\u7684\u6bcf\u4e00\u884c\u76f8\u7d50\u5408\u3002<\/li>\n<\/ul>\n<h2 id=\"%e4%bd%bf%e7%94%a8join%e7%9a%84%e7%af%84%e4%be%8b-TuhXwEVGDe\">\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\u7a31\uff0c\u4e26\u5f9e<code>orders<\/code>\u8868\u4e2d\u9078\u64c7\u8a02\u55ae\u65e5\u671f\u3002JOIN\u689d\u4ef6\u662f\u5ba2\u6236\u7684ID\u5fc5\u9808\u8207\u8a02\u55ae\u4e2d\u7684\u5ba2\u6236ID\u5339\u914d\u3002\u9019\u6a23\uff0c\u6211\u5011\u5c31\u80fd\u7372\u5f97\u6bcf\u4f4d\u5ba2\u6236\u53ca\u5176\u76f8\u61c9\u8a02\u55ae\u7684\u65e5\u671f\u3002<\/p>\n<h2 id=\"join%e7%9a%84%e6%80%a7%e8%83%bd%e8%80%83%e9%87%8f-TuhXwEVGDe\">JOIN\u7684\u6027\u80fd\u8003\u91cf<\/h2>\n<p>\u5728\u4f7f\u7528JOIN\u6642\uff0c\u6027\u80fd\u662f\u4e00\u500b\u91cd\u8981\u7684\u8003\u91cf\u56e0\u7d20\u3002\u7576\u8868\u7684\u5927\u5c0f\u589e\u52a0\u6642\uff0cJOIN\u64cd\u4f5c\u53ef\u80fd\u6703\u8b8a\u5f97\u975e\u5e38\u8017\u6642\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u512a\u5316JOIN\u6027\u80fd\u7684\u5efa\u8b70\uff1a<\/p>\n<ul>\n<li>\u78ba\u4fdd\u5728JOIN\u7684\u6b04\u4f4d\u4e0a\u5efa\u7acb\u7d22\u5f15\uff0c\u9019\u6a23\u53ef\u4ee5\u52a0\u5feb\u67e5\u8a62\u901f\u5ea6\u3002<\/li>\n<li>\u907f\u514d\u5728JOIN\u4e2d\u4f7f\u7528SELECT *\uff0c\u800c\u662f\u9078\u64c7\u9700\u8981\u7684\u6b04\u4f4d\uff0c\u9019\u6a23\u53ef\u4ee5\u6e1b\u5c11\u8cc7\u6599\u50b3\u8f38\u91cf\u3002<\/li>\n<li>\u8003\u616e\u4f7f\u7528EXPLAIN\u8a9e\u53e5\u4f86\u5206\u6790\u67e5\u8a62\u8a08\u5283\uff0c\u627e\u51fa\u6f5b\u5728\u7684\u6027\u80fd\u74f6\u9838\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-TuhXwEVGDe\">\u7e3d\u7d50<\/h2>\n<p>JOIN\u6307\u4ee4\u5728MySQL\u4e2d\u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u80fd\u5920\u5e6b\u52a9\u7528\u6236\u5f9e\u591a\u500b\u8868\u4e2d\u63d0\u53d6\u548c\u7d44\u5408\u8cc7\u6599\u3002\u7121\u8ad6\u662fINNER JOIN\u3001LEFT JOIN\u9084\u662f\u5176\u4ed6\u985e\u578b\u7684JOIN\uff0c\u4e86\u89e3\u5176\u7528\u6cd5\u548c\u6027\u80fd\u8003\u91cf\u90fd\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002\u900f\u904e\u5408\u7406\u7684\u4f7f\u7528JOIN\uff0c\u958b\u767c\u8005\u53ef\u4ee5\u6709\u6548\u5730\u7ba1\u7406\u548c\u67e5\u8a62\u8cc7\u6599\uff0c\u63d0\u5347\u61c9\u7528\u7a0b\u5f0f\u7684\u6027\u80fd\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc\u8cc7\u6599\u5eab\u7ba1\u7406\u6216\u5176\u4ed6\u6280\u8853\u554f\u984c\u6709\u8208\u8da3\uff0c\u6b61\u8fce\u8a2a\u554f\u6211\u5011\u7684\u7db2\u7ad9\u4e86\u89e3\u66f4\u591a\u8cc7\u8a0a\uff0c\u7279\u5225\u662f\u6709\u95dc\u65bc<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u548c<a href=\"https:\/\/server.hk\">\u96f2\u4f3a\u670d\u5668<\/a>\u7684\u89e3\u6c7a\u65b9\u6848\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3MySQL\u4e2d\u7684JOIN\u6307\u4ee4\uff0c\u5b78\u7fd2\u5982\u4f55\u9023\u63a5\u591a\u500b\u8868\u4ee5\u67e5\u8a62\u548c\u6574\u5408\u6578\u64da\uff0c\u63d0\u9ad8\u6578\u64da\u8655\u7406\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-78840","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/78840","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=78840"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/78840\/revisions"}],"predecessor-version":[{"id":78841,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/78840\/revisions\/78841"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=78840"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=78840"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=78840"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}