{"id":76266,"date":"2024-10-16T05:14:14","date_gmt":"2024-10-15T21:14:14","guid":{"rendered":"https:\/\/server.hk\/cnblog\/76266\/"},"modified":"2024-10-16T05:14:14","modified_gmt":"2024-10-15T21:14:14","slug":"mysql%e5%85%a5%e9%96%80%ef%bc%9a%e4%bd%bf%e7%94%a8self-join%e5%b0%87%e4%b8%80%e5%80%8b%e8%a1%a8%e8%88%87%e8%87%aa%e8%ba%ab%e9%80%a3%e6%8e%a5%ef%bc%8c%e5%b0%b1%e5%a5%bd%e5%83%8f%e8%a9%b2%e8%a1%a8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/76266\/","title":{"rendered":"MySQL\u5165\u9580\uff1a\u4f7f\u7528SELF JOIN\u5c07\u4e00\u500b\u8868\u8207\u81ea\u8eab\u9023\u63a5\uff0c\u5c31\u597d\u50cf\u8a72\u8868\u662f\u5169\u500b\u8868\u4e00\u6a23\u3002"},"content":{"rendered":"<h1 id=\"mysql%e5%85%a5%e9%96%80%ef%bc%9a%e4%bd%bf%e7%94%a8self-join%e5%b0%87%e4%b8%80%e5%80%8b%e8%a1%a8%e8%88%87%e8%87%aa%e8%ba%ab%e9%80%a3%e6%8e%a5%ef%bc%8c%e5%b0%b1%e5%a5%bd%e5%83%8f%e8%a9%b2%e8%a1%a8-MJnYETzXlF\">MySQL\u5165\u9580\uff1a\u4f7f\u7528SELF JOIN\u5c07\u4e00\u500b\u8868\u8207\u81ea\u8eab\u9023\u63a5\uff0c\u5c31\u597d\u50cf\u8a72\u8868\u662f\u5169\u500b\u8868\u4e00\u6a23<\/h1>\n<p>\u5728\u6578\u64da\u5eab\u7ba1\u7406\u7cfb\u7d71\u4e2d\uff0cMySQL\u662f\u4e00\u500b\u975e\u5e38\u6d41\u884c\u7684\u9078\u64c7\uff0c\u56e0\u70ba\u5b83\u7684\u9748\u6d3b\u6027\u548c\u5f37\u5927\u7684\u529f\u80fd\u3002\u7576\u6211\u5011\u8655\u7406\u6578\u64da\u6642\uff0c\u7d93\u5e38\u9700\u8981\u5f9e\u540c\u4e00\u500b\u8868\u4e2d\u7372\u53d6\u4e0d\u540c\u7684\u6578\u64da\u3002\u9019\u6642\uff0cSELF JOIN\uff08\u81ea\u9023\u63a5\uff09\u5c31\u6d3e\u4e0a\u7528\u5834\u4e86\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0eSELF JOIN\u7684\u6982\u5ff5\u53ca\u5176\u5728MySQL\u4e2d\u7684\u61c9\u7528\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%afself-join%ef%bc%9f-MJnYETzXlF\">\u4ec0\u9ebc\u662fSELF JOIN\uff1f<\/h2>\n<p>SELF JOIN\u662f\u4e00\u7a2e\u7279\u6b8a\u7684JOIN\u64cd\u4f5c\uff0c\u5141\u8a31\u6211\u5011\u5c07\u4e00\u500b\u8868\u8207\u81ea\u8eab\u9032\u884c\u9023\u63a5\u3002\u9019\u610f\u5473\u8457\u6211\u5011\u53ef\u4ee5\u5728\u540c\u4e00\u500b\u8868\u4e2d\u67e5\u8a62\u4e0d\u540c\u7684\u884c\uff0c\u4e26\u5c07\u5b83\u5011\u8996\u70ba\u5169\u500b\u4e0d\u540c\u7684\u8868\u3002\u9019\u5728\u8655\u7406\u5c64\u7d1a\u7d50\u69cb\u6216\u9700\u8981\u6bd4\u8f03\u540c\u4e00\u8868\u4e2d\u4e0d\u540c\u6578\u64da\u6642\u7279\u5225\u6709\u7528\u3002<\/p>\n<h2 id=\"self-join%e7%9a%84%e5%9f%ba%e6%9c%ac%e8%aa%9e%e6%b3%95-MJnYETzXlF\">SELF JOIN\u7684\u57fa\u672c\u8a9e\u6cd5<\/h2>\n<p>SELF JOIN\u7684\u57fa\u672c\u8a9e\u6cd5\u8207\u5176\u4ed6JOIN\u985e\u4f3c\uff0c\u4f46\u9700\u8981\u4f7f\u7528\u8868\u7684\u5225\u540d\u4f86\u5340\u5206\u540c\u4e00\u8868\u7684\u4e0d\u540c\u5be6\u4f8b\u3002\u4ee5\u4e0b\u662fSELF JOIN\u7684\u57fa\u672c\u8a9e\u6cd5\uff1a<\/p>\n<pre><code>\nSELECT a.column1, b.column2\nFROM table_name AS a\nJOIN table_name AS b ON a.common_field = b.common_field;\n<\/code><\/pre>\n<h2 id=\"self-join%e7%9a%84%e5%af%a6%e9%9a%9b%e6%87%89%e7%94%a8-MJnYETzXlF\">SELF JOIN\u7684\u5be6\u969b\u61c9\u7528<\/h2>\n<p>\u70ba\u4e86\u66f4\u597d\u5730\u7406\u89e3SELF JOIN\uff0c\u8b93\u6211\u5011\u8003\u616e\u4e00\u500b\u5177\u9ad4\u7684\u4f8b\u5b50\u3002\u5047\u8a2d\u6211\u5011\u6709\u4e00\u500b\u540d\u70ba\u201c\u54e1\u5de5\u201d\u7684\u8868\uff0c\u8a72\u8868\u5305\u542b\u4ee5\u4e0b\u5b57\u6bb5\uff1a<\/p>\n<ul>\n<li>\u54e1\u5de5ID (employee_id)<\/li>\n<li>\u59d3\u540d (name)<\/li>\n<li>\u4e0a\u7d1aID (manager_id)<\/li>\n<\/ul>\n<p>\u9019\u500b\u8868\u7684\u7d50\u69cb\u53ef\u80fd\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<pre><code>\n+------------+----------+------------+\n| employee_id| name     | manager_id |\n+------------+----------+------------+\n| 1          | Alice    | NULL       |\n| 2          | Bob      | 1          |\n| 3          | Charlie   | 1          |\n| 4          | David    | 2          |\n+------------+----------+------------+\n<\/code><\/pre>\n<p>\u5728\u9019\u500b\u4f8b\u5b50\u4e2d\uff0cAlice\u662fBob\u548cCharlie\u7684\u4e0a\u7d1a\uff0c\u800cBob\u662fDavid\u7684\u4e0a\u7d1a\u3002\u5982\u679c\u6211\u5011\u60f3\u8981\u67e5\u8a62\u6bcf\u4f4d\u54e1\u5de5\u53ca\u5176\u4e0a\u7d1a\u7684\u59d3\u540d\uff0c\u6211\u5011\u53ef\u4ee5\u4f7f\u7528SELF JOIN\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<pre><code>\nSELECT a.name AS Employee, b.name AS Manager\nFROM employees AS a\nLEFT JOIN employees AS b ON a.manager_id = b.employee_id;\n<\/code><\/pre>\n<p>\u9019\u6bb5\u67e5\u8a62\u5c07\u8fd4\u56de\u6bcf\u4f4d\u54e1\u5de5\u53ca\u5176\u4e0a\u7d1a\u7684\u59d3\u540d\uff0c\u7d50\u679c\u5982\u4e0b\uff1a<\/p>\n<pre><code>\n+----------+---------+\n| Employee | Manager |\n+----------+---------+\n| Alice    | NULL    |\n| Bob      | Alice   |\n| Charlie   | Alice   |\n| David    | Bob     |\n+----------+---------+\n<\/code><\/pre>\n<h2 id=\"%e6%b3%a8%e6%84%8f%e4%ba%8b%e9%a0%85-MJnYETzXlF\">\u6ce8\u610f\u4e8b\u9805<\/h2>\n<p>\u5728\u4f7f\u7528SELF JOIN\u6642\uff0c\u6709\u5e7e\u9ede\u9700\u8981\u6ce8\u610f\uff1a<\/p>\n<ul>\n<li>\u4f7f\u7528\u5225\u540d\uff1a\u7531\u65bc\u6211\u5011\u5728\u540c\u4e00\u8868\u4e2d\u9032\u884c\u9023\u63a5\uff0c\u4f7f\u7528\u5225\u540d\u53ef\u4ee5\u5e6b\u52a9\u6211\u5011\u6e05\u6670\u5730\u5340\u5206\u4e0d\u540c\u7684\u5be6\u4f8b\u3002<\/li>\n<li>\u6027\u80fd\u8003\u91cf\uff1aSELF JOIN\u53ef\u80fd\u6703\u5c0e\u81f4\u6027\u80fd\u554f\u984c\uff0c\u7279\u5225\u662f\u5728\u8655\u7406\u5927\u578b\u6578\u64da\u96c6\u6642\u3002\u56e0\u6b64\uff0c\u61c9\u8b39\u614e\u4f7f\u7528\uff0c\u4e26\u8003\u616e\u5176\u4ed6\u512a\u5316\u65b9\u6cd5\u3002<\/li>\n<li>\u6578\u64da\u5b8c\u6574\u6027\uff1a\u78ba\u4fdd\u5728\u9032\u884cSELF JOIN\u6642\uff0c\u6240\u7528\u7684\u9023\u63a5\u689d\u4ef6\u662f\u6b63\u78ba\u7684\uff0c\u4ee5\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u6578\u64da\u91cd\u8907\u6216\u932f\u8aa4\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-MJnYETzXlF\">\u7e3d\u7d50<\/h2>\n<p>SELF JOIN\u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u80fd\u5920\u5e6b\u52a9\u6211\u5011\u5728MySQL\u4e2d\u9748\u6d3b\u5730\u67e5\u8a62\u540c\u4e00\u8868\u4e2d\u7684\u6578\u64da\u3002\u901a\u904e\u4f7f\u7528\u5225\u540d\u548c\u6b63\u78ba\u7684\u9023\u63a5\u689d\u4ef6\uff0c\u6211\u5011\u53ef\u4ee5\u8f15\u9b06\u5730\u7372\u53d6\u6240\u9700\u7684\u4fe1\u606f\u3002\u7121\u8ad6\u662f\u5728\u8655\u7406\u5c64\u7d1a\u7d50\u69cb\u9084\u662f\u9032\u884c\u6578\u64da\u6bd4\u8f03\uff0cSELF JOIN\u90fd\u80fd\u63d0\u4f9b\u6709\u6548\u7684\u89e3\u6c7a\u65b9\u6848\u3002<\/p>\n<p>\u5982\u679c\u60a8\u5c0d\u65bc\u6578\u64da\u5eab\u7ba1\u7406\u6709\u66f4\u6df1\u5165\u7684\u9700\u6c42\uff0c\u8003\u616e\u4f7f\u7528<a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a>\u4f86\u642d\u5efa\u60a8\u7684\u6578\u64da\u5eab\u74b0\u5883\uff0c\u4eab\u53d7\u66f4\u9ad8\u7684\u6027\u80fd\u548c\u7a69\u5b9a\u6027\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5b78\u7fd2MySQL\u5165\u9580\uff0c\u900f\u904eSELF JOIN\u5c07\u4e00\u500b\u8868\u8207\u81ea\u8eab\u9023\u63a5\uff0c\u8f15\u9b06\u638c\u63e1\u5982\u4f55\u50cf\u64cd\u4f5c\u5169\u500b\u8868\u4e00\u6a23\u9032\u884c\u67e5\u8a62\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-76266","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/76266","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=76266"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/76266\/revisions"}],"predecessor-version":[{"id":76267,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/76266\/revisions\/76267"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=76266"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=76266"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=76266"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}