{"id":112,"date":"2023-11-17T17:28:00","date_gmt":"2023-11-17T09:28:00","guid":{"rendered":"http:\/\/www.cmd137blog.top\/?p=112"},"modified":"2024-04-01T17:29:20","modified_gmt":"2024-04-01T09:29:20","slug":"sql-%e5%a4%9a%e8%a1%a8%e6%9f%a5%e8%af%a2-%e8%87%aa%e8%bf%9e%e6%8e%a5","status":"publish","type":"post","link":"http:\/\/www.cmd137blog.top\/?p=112","title":{"rendered":"SQL-\u591a\u8868\u67e5\u8be2-\u81ea\u8fde\u63a5"},"content":{"rendered":"\n

\u4e00\u3001\u524d\u8a00<\/h1>\n\n\n\n

\u5728 SQL \u4e2d\uff0c\u81ea\u8fde\u63a5\uff08Self-Join\uff09\u6307\u7684\u662f\u5728\u540c\u4e00\u4e2a\u8868\u4e2d\u8fdb\u884c JOIN \u64cd\u4f5c\u3002\u901a\u8fc7\u81ea\u8fde\u63a5\uff0c\u6211\u4eec\u53ef\u4ee5\u5c06\u8868\u4e2d\u7684\u4e0d\u540c\u884c\u4e4b\u95f4\u8fdb\u884c\u5173\u8054\uff0c\u8fdb\u884c\u6bd4\u8f83\u548c\u5206\u6790\u7b49\u64cd\u4f5c\u3002<\/p>\n\n\n\n

\u672c\u7bc7\u6587\u7ae0\u5c06\u8be6\u7ec6\u8bb2\u89e3 SQL \u7684\u81ea\u8fde\u63a5\uff0c\u5305\u62ec\u81ea\u8fde\u63a5\u7684\u610f\u4e49\u3001\u7528\u6cd5\u3001\u4ee5\u53ca\u9002\u7528\u573a\u666f\u3002<\/p>\n\n\n\n

\n\n\n\n

\u4e00\u3001\u81ea\u8fde\u63a5\u662f\u4ec0\u4e48\uff1f<\/h1>\n\n\n\n

\u81ea\u8fde\u63a5\u662f\u5728\u5173\u7cfb\u578b\u6570\u636e\u5e93\u4e2d\u4f7f\u7528\u540c\u4e00\u5f20\u8868\u8fdb\u884c\u8fde\u63a5\u64cd\u4f5c\u7684\u4e00\u79cd\u6280\u672f\u3002\u901a\u5e38\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u4f7f\u7528JOIN\u64cd\u4f5c\u6765\u8fde\u63a5\u591a\u5f20\u8868\uff0c\u4ee5\u83b7\u53d6\u76f8\u5173\u7684\u6570\u636e\u3002\u4f46\u662f\u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u9700\u8981\u5728\u540c\u4e00\u5f20\u8868\u4e2d\u67e5\u627e\u4e0d\u540c\u884c\u4e4b\u95f4\u7684\u5173\u8054\u6570\u636e\uff0c\u8fd9\u65f6\u5c31\u53ef\u4ee5\u4f7f\u7528\u81ea\u8fde\u63a5\u3002<\/p>\n\n\n\n

\u81ea\u8fde\u63a5\u901a\u8fc7\u5728\u67e5\u8be2\u4e2d\u4f7f\u7528\u540c\u4e00\u5f20\u8868\u7684\u522b\u540d\u6765\u521b\u5efa\u4e24\u4e2a\u6216\u591a\u4e2a\u8868\u7684\u5b9e\u4f8b\uff0c\u5e76\u4f7f\u7528\u7ea6\u675f\u6761\u4ef6\u6765\u8fde\u63a5\u5b83\u4eec\u3002\u8fd9\u6837\uff0c\u53ef\u4ee5\u6bd4\u8f83\u540c\u4e00\u8868\u4e2d\u7684\u4e0d\u540c\u8bb0\u5f55\u4e4b\u95f4\u7684\u67d0\u4e9b\u5b57\u6bb5\uff0c\u4ece\u800c\u5b9e\u73b0\u5404\u79cd\u67e5\u8be2\u548c\u5206\u6790\u64cd\u4f5c\u3002<\/p>\n\n\n\n

\u4e8c\u3001\u4f7f\u7528<\/h1>\n\n\n\n

1.\u8bed\u6cd5<\/h2>\n\n\n\n
\n

SELECT \u5b57\u6bb5\u5217\u8868 FROM \u88681 \u522b\u540d1 JOIN \u88681 \u522b\u540d2 ON \u6761\u4ef6\u2026\uff1b<\/p>\n\n\n\n

\u6ce8\u610f\uff01\uff01\uff01<\/em><\/strong>\uff1a\u5f53\u524d\u8868\u4e0e\u81ea\u8eab\u7684\u8fde\u63a5\u67e5\u8be2\uff0c\u81ea\u8fde\u63a5\u5fc5\u987b\u4f7f\u7528\u8868\u522b\u540d\uff08\u89c6\u4f5c\u4e24\u4e2a\u8868\uff09<\/p>\n<\/blockquote>\n\n\n\n

\u81ea\u8fde\u63a5\u67e5\u8be2\uff0c\u53ef\u4ee5\u662f\u5185\u8fde\u63a5\u67e5\u8be2\uff0c\u4e5f\u53ef\u4ee5\u662f\u5916\u8fde\u63a5\u67e5\u8be2\uff1a
\u5982\uff1a<\/p>\n\n\n\n

 -- \u67e5\u8be2\u5458\u5de5\u53ca\u5176\u6240\u5c5e\u9886\u5bfc\u7684\u540d\u5b57\nselect a.name, b.name from employee a, employee b where a.manager = b.id;\n-- \u6ca1\u6709\u9886\u5bfc\u7684\u4e5f\u67e5\u8be2\u51fa\u6765\nselect a.name, b.name from employee a left join employee b on a.manager = b.id;<\/code><\/pre>\n\n\n\n
2.\u4f7f\u7528\u573a\u666f\uff1a<\/h2>\n\n\n\n
\n
1.\u5c42\u7ea7\u67e5\u8be2\uff1a\u4f7f\u7528\u81ea\u8fde\u63a5\u53ef\u4ee5\u67e5\u8be2\u5c42\u7ea7\u7ed3\u6784\u4e2d\u7684\u6570\u636e\uff0c\u4f8b\u5982\u5458\u5de5\u4e0e\u76f4\u63a5\u4e0a\u7ea7\u7684\u5173\u7cfb\u3002
2.\u6570\u636e\u7684\u81ea\u5173\u8054\uff1a\u4f7f\u7528\u81ea\u8fde\u63a5\u67e5\u627e\u4e0e\u7ed9\u5b9a\u8bb0\u5f55\u76f8\u5173\u7684\u5176\u4ed6\u8bb0\u5f55\uff0c\u4f8b\u5982\u8ba2\u5355\u4e0e\u76f8\u5173\u8ba2\u5355\u7684\u5173\u7cfb\u3002
3.\u5217\u51fa\u6ca1\u6709\u5339\u914d\u8bb0\u5f55\u7684\u6570\u636e\uff1a\u4f7f\u7528\u81ea\u8fde\u63a5\u67e5\u627e\u5728\u67d0\u4e2a\u5b57\u6bb5\u4e0a\u6ca1\u6709\u5339\u914d\u8bb0\u5f55\u7684\u6570\u636e\uff0c\u4f8b\u5982\u6ca1\u6709\u76f8\u5173\u4ea7\u54c1\u7684\u4ea7\u54c1\u8bb0\u5f55\u3002
4.\u9012\u5f52\u67e5\u8be2\uff1a\u4f7f\u7528\u81ea\u8fde\u63a5\u5904\u7406\u9012\u5f52\u7ed3\u6784\uff0c\u4f8b\u5982\u6811\u5f62\u7ed3\u6784\u4e2d\u7684\u5b50\u8282\u70b9\u548c\u7236\u8282\u70b9\u7684\u76f8\u5173\u67e5\u8be2\u3002<\/p>\n<\/blockquote>\n\n\n\n
\n\n\n\n
\u4e09\u3001\u603b\u7ed3<\/h1>\n\n\n\n
\u81ea\u8fde\u63a5\u662f SQL \u4e2d\u5f3a\u5927\u4e14\u6709\u7528\u7684\u6280\u672f\uff0c\u53ef\u4ee5\u7528\u4e8e\u6bd4\u8f83\u540c\u4e00\u5f20\u8868\u4e2d\u7684\u4e0d\u540c\u884c\u3001\u67e5\u627e\u6570\u636e\u3001\u8ba1\u7b97\u548c\u5206\u6790\u6570\u636e\uff0c\u4ee5\u53ca\u5904\u7406\u5c42\u7ea7\u7ed3\u6784\u7b49\u3002\u901a\u8fc7\u5408\u7406\u5229\u7528\u81ea\u8fde\u63a5\uff0c\u53ef\u4ee5\u5b9e\u73b0\u66f4\u590d\u6742\u548c\u6df1\u5165\u7684\u67e5\u8be2\u548c\u5206\u6790\u64cd\u4f5c\u3002\u5728\u4f7f\u7528\u81ea\u8fde\u63a5\u65f6\uff0c<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e00\u3001\u524d\u8a00 \u5728 SQL \u4e2d\uff0c\u81ea\u8fde\u63a5\uff08Self-Join\uff09\u6307\u7684\u662f\u5728\u540c\u4e00\u4e2a\u8868\u4e2d\u8fdb\u884c JOIN \u64cd\u4f5c\u3002\u901a\u8fc7\u81ea\u8fde\u63a5\uff0c\u6211\u4eec […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[14,15,18],"class_list":["post-112","post","type-post","status-publish","format-standard","hentry","category-sql","tag-sql","tag-15","tag-18"],"_links":{"self":[{"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/posts\/112","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=112"}],"version-history":[{"count":1,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/posts\/112\/revisions"}],"predecessor-version":[{"id":113,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=\/wp\/v2\/posts\/112\/revisions\/113"}],"wp:attachment":[{"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=112"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=112"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.cmd137blog.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=112"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}