{"id":200810,"date":"2025-05-06T13:02:26","date_gmt":"2025-05-06T05:02:26","guid":{"rendered":"https:\/\/server.hk\/cnblog\/200810\/"},"modified":"2025-05-06T13:02:26","modified_gmt":"2025-05-06T05:02:26","slug":"%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8-sql-%e6%9f%a5%e8%af%a2%e5%8e%bb%e9%87%8d%e6%8a%80%e5%b7%a7%e5%8e%bb%e9%99%a4%e9%87%8d%e5%a4%8d%e6%95%b0%e6%8d%ae%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/200810\/","title":{"rendered":"\u5982\u4f55\u4f7f\u7528 SQL \u67e5\u8be2\u53bb\u91cd\u6280\u5de7\u53bb\u9664\u91cd\u590d\u6570\u636e\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<h1>\u5982\u4f55\u4f7f\u7528 SQL \u67e5\u8be2\u53bb\u91cd\u6280\u5de7\u53bb\u9664\u91cd\u590d\u6570\u636e\uff1f<\/h1>\n<p>\u4ece\u73b0\u5728\u5f00\u59cb\uff0c\u52aa\u529b\u5b66\u4e60\u5427\uff01\u672c\u6587\u4e3b\u8981\u8bb2\u89e3\u4e86\u7b49\u7b49\u76f8\u5173\u77e5\u8bc6\u70b9\uff0c\u6211\u4f1a\u5728\u4e3b\u673a\u5b9d\u8d1d\u4e2d\u6301\u7eed\u66f4\u65b0\u76f8\u5173\u7684\u7cfb\u5217\u6587\u7ae0\uff0c\u6b22\u8fce\u5927\u5bb6\u5173\u6ce8\u5e76\u79ef\u6781\u7559\u8a00\u5efa\u8bae\u3002\u4e0b\u9762\u5c31\u5148\u4e00\u8d77\u6765\u770b\u4e00\u4e0b\u672c\u7bc7\u6b63\u6587\u5185\u5bb9\u5427\uff0c\u5e0c\u671b\u80fd\u5e2e\u5230\u4f60\uff01<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241115\/17316670066737243e7f0b9.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>sql \u67e5\u8be2\u53bb\u91cd\u6280\u5de7<\/strong><\/p>\n<p>\u5728\u67e5\u8be2\u4e2d\u53bb\u9664\u91cd\u590d\u6570\u636e\u662f\u4e00\u4e2a\u5e38\u89c1\u7684\u9700\u6c42\u3002\u5bf9\u4e8e\u7c7b\u4f3c\u4e8e\u67e5\u8be2\u4e2d\u6240\u63cf\u8ff0\u7684\u573a\u666f\uff0c\u53ef\u4ee5\u4f7f\u7528 left join \u8bed\u53e5\uff0c\u4ee5\u4e00\u4e2a\u8868\u4f5c\u4e3a\u4e3b\u8868\uff0c\u53e6\u4e00\u4e2a\u8868\u4f5c\u4e3a\u4ece\u8868\uff0c\u5e76\u4f7f\u7528 distinct \u5173\u952e\u5b57\u6765\u53bb\u9664\u91cd\u590d\u7684\u7ed3\u679c\u3002<\/p>\n<p>\u4f46\u662f\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u56e0\u4e3a\u4ece\u8868\u4e2d\u8ddf\u8e2a\u53f7\uff08tracking_number\uff09\u7684\u4e0d\u540c\uff0c\u4f1a\u5bfc\u81f4\u51fa\u73b0\u91cd\u590d\u7684\u59d3\u540d\uff0c\u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\uff0c\u9700\u8981\u5728\u4ece\u8868\u4e2d\u9009\u53d6\u552f\u4e00\u7684\u4e00\u884c\u3002\u53ef\u4ee5\u901a\u8fc7\u4f7f\u7528\u805a\u5408\u51fd\u6570\uff0c\u4f8b\u5982 max() \u6216 min()\uff0c\u6765\u5b9e\u73b0\u3002<\/p>\n<p>\u8fd9\u91cc\u63d0\u4f9b\u4e86\u4e00\u4e2a\u6539\u8fdb\u7684 sql \u67e5\u8be2\uff1a<\/p>\n<pre>SELECT *\nFROM a\nLEFT JOIN (\n    SELECT sid, MAX(tracking_number) AS tracking_number\n    FROM b\n    GROUP BY sid\n) b\nON a.sid = b.sid<\/pre>\n<p>\u5229\u7528 max() \u51fd\u6570\uff0c\u53ef\u4ee5\u9009\u53d6\u6bcf\u4e2a sid\uff08a \u8868\u4e2d\u7684\u4e3b\u952e\uff09\u5bf9\u5e94\u7684\u6700\u5927\u8ddf\u8e2a\u53f7\uff0c\u4ece\u800c\u53ea\u4fdd\u7559\u552f\u4e00\u4e00\u884c\u3002\u8fd9\u6837\u4e00\u6765\uff0c\u67e5\u8be2\u7ed3\u679c\u4e2d\u5c06\u4e0d\u518d\u51fa\u73b0\u91cd\u590d\u7684\u59d3\u540d\u3002<\/p>\n<p>\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u4e0d\u540c\u7684\u6570\u636e\u5e93\u53ef\u80fd\u9700\u8981\u4e0d\u540c\u7684\u8bed\u6cd5\u3002\u4f8b\u5982\uff0c\u6709\u4e9b\u6570\u636e\u5e93\u53ef\u80fd\u4e0d\u9700\u8981 max() \u51fd\u6570\uff0c\u800c\u662f\u53ef\u4ee5\u76f4\u63a5\u4f7f\u7528\u8ddf\u8e2a\u53f7\u3002<\/p>\n<p>\u4ee5\u4e0a\u5c31\u662f\u672c\u6587\u7684\u5168\u90e8\u5185\u5bb9\u4e86\uff0c\u662f\u5426\u6709\u987a\u5229\u5e2e\u52a9\u4f60\u89e3\u51b3\u95ee\u9898\uff1f\u82e5\u662f\u80fd\u7ed9\u4f60\u5e26\u6765\u5b66\u4e60\u4e0a\u7684\u5e2e\u52a9\uff0c\u8bf7\u5927\u5bb6\u591a\u591a\u652f\u6301\u4e3b\u673a\u5b9d\u8d1d\uff01\u66f4\u591a\u5173\u4e8e\u6570\u636e\u5e93\u7684\u76f8\u5173\u77e5\u8bc6\uff0c\u4e5f\u53ef\u5173\u6ce8\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\u3002<\/p>\n<dl>\n<dt>\n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"<p>\u5982\u4f55\u4f7f\u7528 SQL \u67e5\u8be2\u53bb\u91cd\u6280\u5de7\u53bb&#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-200810","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200810","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=200810"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/200810\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=200810"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=200810"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=200810"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}