{"id":200458,"date":"2025-05-06T08:29:38","date_gmt":"2025-05-06T00:29:38","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200458\/"},"modified":"2025-05-06T08:29:38","modified_gmt":"2025-05-06T00:29:38","slug":"%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8mysql-left-join-%e6%9b%b4%e6%96%b0%e5%ad%a6%e7%94%9f%e8%a1%a8%e4%b8%ad%e6%88%90%e7%bb%a9%e5%ad%97%e6%ae%b5%e4%b8%ba%e5%af%b9%e5%ba%94%e5%ad%a6%e7%94%9f%e5%9c%a8","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200458\/","title":{"rendered":"\u5982\u4f55\u4f7f\u7528MySQL left join \u66f4\u65b0\u5b66\u751f\u8868\u4e2d\u6210\u7ee9\u5b57\u6bb5\u4e3a\u5bf9\u5e94\u5b66\u751f\u5728\u6210\u7ee9\u8868\u4e2d\u7684\u6700\u9ad8\u5206\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<h1>\u5982\u4f55\u4f7f\u7528MySQL left join \u66f4\u65b0\u5b66\u751f\u8868\u4e2d\u6210\u7ee9\u5b57\u6bb5\u4e3a\u5bf9\u5e94\u5b66\u751f\u5728\u6210\u7ee9\u8868\u4e2d\u7684\u6700\u9ad8\u5206\uff1f<\/h1>\n<p>\u201c\u7eb5\u6709\u75be\u98ce\u6765\uff0c\u4eba\u751f\u4e0d\u8a00\u5f03\u201d\uff0c\u8fd9\u53e5\u8bdd\u9001\u7ed9\u6b63\u5728\u5b66\u4e60\u7684\u670b\u53cb\u4eec\uff0c\u4e5f\u5e0c\u671b\u5728\u9605\u8bfb\u672c\u6587\u540e\uff0c\u80fd\u591f\u771f\u7684\u5e2e\u52a9\u5230\u5927\u5bb6\u3002\u6211\u4e5f\u4f1a\u5728\u540e\u7eed\u7684\u6587\u7ae0\u4e2d\uff0c\u9646\u7eed\u66f4\u65b0\u76f8\u5173\u7684\u6280\u672f\u6587\u7ae0\uff0c\u6709\u597d\u7684\u5efa\u8bae\u6b22\u8fce\u5927\u5bb6\u5728\u8bc4\u8bba\u7559\u8a00\uff0c\u975e\u5e38\u611f\u8c22\uff01<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241105\/17308011996729ee2feaaf3.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>mysql left join \u5b9e\u73b0\u591a\u6761\u6570\u636e\u4e2d\u67d0\u5b57\u6bb5\u6700\u5927\u503c\u7684\u66f4\u65b0<\/strong><\/p>\n<p>\u5728mysql\u4e2d\uff0c\u5bf9\u4e8e\u66f4\u65b0student\u8868\u4e2dscore\u5b57\u6bb5\u7684\u503c\uff0c\u4f7f\u5176\u7b49\u4e8escore\u8868\u4e2d\u5bf9\u5e94student_id\u7684\u6700\u5927\u503c\uff0c\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u65b9\u6cd5\uff1a<\/p>\n<p><strong>\u67e5\u8be2\u8bed\u53e5\uff1a<\/strong><\/p>\n<pre>update student set score=(select max(score) from score where score.student_id=student.id)<\/pre>\n<p><strong>\u89e3\u91ca\uff1a<\/strong><\/p>\n<ul>\n<li><strong>left join:<\/strong> \u5c06student\u8868\u548cscore\u8868\u4ee5student_id\u5217\u8fdb\u884c\u8fde\u63a5\uff0c\u5bf9\u4e8estudent\u8868\u4e2d\u7684\u6bcf\u4e00\u884c\uff0c\u627e\u51fascore\u8868\u4e2d\u5bf9\u5e94\u7684\u6700\u5927score\u503c\u3002<\/li>\n<li><strong>max(score):<\/strong> \u83b7\u53d6\u5f97\u5206\u8868\u4e2d\u7279\u5b9a\u5b66\u751f\u5f97\u5206\u7684\u6700\u5927\u503c\u3002<\/li>\n<li><strong>where score.student_id=student.id:<\/strong> \u786e\u4fddscore\u8868\u7684student_id\u4e0estudent\u8868\u7684student_id\u5339\u914d\u3002<\/li>\n<li><strong>update student set score=():<\/strong> \u5c06student\u8868\u7684score\u5b57\u6bb5\u66f4\u65b0\u4e3a\u4ece( )\u4e2d\u9009\u51fa\u7684\u6700\u5927\u503c\u3002<\/li>\n<\/ul>\n<p>\u6267\u884c\u6b64\u67e5\u8be2\u540e\uff0cstudent\u8868\u4e2d\u6bcf\u4e2a\u5b66\u751f\u7684score\u5b57\u6bb5\u5c06\u66f4\u65b0\u4e3a\u4ed6\u4eec\u5728score\u8868\u4e2d\u83b7\u5f97\u7684\u6700\u9ad8\u5206\u6570\u3002<\/p>\n<p>\u7ec8\u4e8e\u4ecb\u7ecd\u5b8c\u5566\uff01\u5c0f\u4f19\u4f34\u4eec\uff0c\u8fd9\u7bc7\u5173\u4e8e\u300a\u5982\u4f55\u4f7f\u7528MySQL left join \u66f4\u65b0\u5b66\u751f\u8868\u4e2d\u6210\u7ee9\u5b57\u6bb5\u4e3a\u5bf9\u5e94\u5b66\u751f\u5728\u6210\u7ee9\u8868\u4e2d\u7684\u6700\u9ad8\u5206\uff1f\u300b\u7684\u4ecb\u7ecd\u5e94\u8be5\u8ba9\u4f60\u6536\u83b7\u591a\u591a\u4e86\u5427\uff01\u6b22\u8fce\u5927\u5bb6\u6536\u85cf\u6216\u5206\u4eab\u7ed9\u66f4\u591a\u9700\u8981\u5b66\u4e60\u7684\u670b\u53cb\u5427~\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\u4e5f\u4f1a\u53d1\u5e03\u6570\u636e\u5e93\u76f8\u5173\u77e5\u8bc6\uff0c\u5feb\u6765\u5173\u6ce8\u5427\uff01<\/p>\n<dl>\n<dt>\n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"<p>\u5982\u4f55\u4f7f\u7528MySQL left j&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-200458","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200458","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"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=200458"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200458\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=200458"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=200458"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=200458"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}