{"id":201002,"date":"2025-05-06T10:48:55","date_gmt":"2025-05-06T02:48:55","guid":{"rendered":"https:\/\/server.hk\/cnblog\/201002\/"},"modified":"2025-05-06T10:48:55","modified_gmt":"2025-05-06T02:48:55","slug":"sql-%e6%9f%a5%e8%af%a2%e6%b1%82%e5%8a%a9%ef%bc%9a%e5%a6%82%e4%bd%95%e4%bb%8e%e4%b8%a4%e5%bc%a0%e8%a1%a8%e4%b8%ad%e8%8e%b7%e5%8f%96%e5%94%af%e4%b8%80%e7%bb%93%e6%9e%9c%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/201002\/","title":{"rendered":"SQL \u67e5\u8be2\u6c42\u52a9\uff1a\u5982\u4f55\u4ece\u4e24\u5f20\u8868\u4e2d\u83b7\u53d6\u552f\u4e00\u7ed3\u679c\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<h1>SQL \u67e5\u8be2\u6c42\u52a9\uff1a\u5982\u4f55\u4ece\u4e24\u5f20\u8868\u4e2d\u83b7\u53d6\u552f\u4e00\u7ed3\u679c\uff1f<\/h1>\n<p>\u600e\u4e48\u5165\u95e8\u6570\u636e\u5e93\u7f16\u7a0b\uff1f\u9700\u8981\u5b66\u4e60\u54ea\u4e9b\u77e5\u8bc6\u70b9\uff1f\u8fd9\u662f\u65b0\u624b\u4eec\u521a\u63a5\u89e6\u7f16\u7a0b\u65f6\u5e38\u89c1\u7684\u95ee\u9898\uff1b\u4e0b\u9762\u4e3b\u673a\u5b9d\u8d1d\u5c31\u6765\u7ed9\u5927\u5bb6\u6574\u7406\u5206\u4eab\u4e00\u4e9b\u77e5\u8bc6\u70b9\uff0c\u5e0c\u671b\u80fd\u591f\u7ed9\u521d\u5b66\u8005\u4e00\u4e9b\u5e2e\u52a9\u3002\u672c\u7bc7\u6587\u7ae0\u5c31\u6765\u4ecb\u7ecd\u300aSQL \u67e5\u8be2\u6c42\u52a9\uff1a\u5982\u4f55\u4ece\u4e24\u5f20\u8868\u4e2d\u83b7\u53d6\u552f\u4e00\u7ed3\u679c\uff1f\u300b\uff0c\u6d89\u53ca\u5230\uff0c\u6709\u9700\u8981\u7684\u53ef\u4ee5\u6536\u85cf\u4e00\u4e0b<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.17golang.com\/uploads\/20241125\/17324980596743d28bf0d32.jpg\" class=\"aligncenter\"><\/p>\n<p><strong>sql \u67e5\u8be2\u6c42\u52a9\uff1a\u5982\u4f55\u4ece\u4e24\u5f20\u8868\u4e2d\u67e5\u8be2\u4e0d\u91cd\u590d\u7ed3\u679c<\/strong><\/p>\n<p>\u672c\u6587\u5c06\u89e3\u51b3\u4e00\u4e2a\u5e38\u89c1\u7684 sql \u67e5\u8be2\u95ee\u9898\uff0c\u8be5\u95ee\u9898\u6d89\u53ca\u4ece\u4e24\u5f20\u8868\u4e2d\u67e5\u8be2\u4e0d\u91cd\u590d\u7684\u7ed3\u679c\u3002<\/p>\n<p><strong>\u95ee\u9898\u63cf\u8ff0\uff1a<\/strong><\/p>\n<p>\u5047\u8bbe\u6211\u4eec\u6709\u4e24\u5f20\u8868\uff0ca \u548c b\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<p>a \u8868\uff1a<\/p>\n<table>\n<thead>\n<tr>\n<th>sid<\/th>\n<th>name<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>1<\/td>\n<td>\u5f20\u4e09<\/td>\n<\/tr>\n<tr>\n<td>2<\/td>\n<td>\u674e\u56db<\/td>\n<\/tr>\n<tr>\n<td>3<\/td>\n<td>\u738b\u4e94<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>b \u8868\uff1a<\/p>\n<table>\n<thead>\n<tr>\n<th>sid<\/th>\n<th>tracking_number<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>1<\/td>\n<td>123<\/td>\n<\/tr>\n<tr>\n<td>1<\/td>\n<td>456<\/td>\n<\/tr>\n<tr>\n<td>2<\/td>\n<td>789<\/td>\n<\/tr>\n<tr>\n<td>3<\/td>\n<td>101<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u6211\u4eec\u7684\u76ee\u6807\u662f\u67e5\u8be2\u4e00\u6761 sql \u8bed\u53e5\uff0c\u4ee5 a \u8868\u4e3a\u57fa\u51c6\uff0c\u83b7\u53d6\u4e0d\u91cd\u590d\u7684\u7ed3\u679c\uff0c\u8fd9\u610f\u5473\u7740\u5bf9\u4e8e\u5177\u6709\u76f8\u540c sid \u7684\u8bb0\u5f55\uff0c\u6211\u4eec\u53ea\u9700\u8981\u4fdd\u7559\u4e00\u884c\u7ed3\u679c\u3002<\/p>\n<p><strong>\u89e3\u51b3\u65b9\u6848\uff1a<\/strong><\/p>\n<p>\u53ef\u4ee5\u4f7f\u7528 left join \u548c\u5b50\u67e5\u8be2\u6765\u5b9e\u73b0\u6240\u9700\u7684\u7ed3\u679c\uff1a<\/p>\n<pre>select *\nfrom a\nleft join (\n  select sid, max(tracking_number)\n  from b\n  group by sid\n) b\non a.sid = b.sid;<\/pre>\n<p>\u5b50\u67e5\u8be2\u7528\u4e8e\u4ece b \u8868\u4e2d\u83b7\u53d6\u6bcf\u4e2a sid \u7684\u6700\u5927\u8ddf\u8e2a\u53f7\u3002\u7136\u540e\uff0c\u6211\u4eec\u4f7f\u7528 left join \u5c06\u6b64\u5b50\u67e5\u8be2\u4e0e a \u8868\u5173\u8054\uff0c\u5e76\u9009\u62e9 a \u8868\u4e2d\u7684\u6240\u6709\u5217\u4ee5\u53ca b \u8868\u4e2d\u7684\u8ddf\u8e2a\u53f7\u3002<\/p>\n<p><strong>\u66ff\u4ee3\u65b9\u6848\uff1a<\/strong><\/p>\n<p>\u5bf9\u4e8e\u67d0\u4e9b\u6570\u636e\u5e93\uff0c\u5982 mysql\uff0c\u53ef\u4ee5\u4f7f\u7528 group by \u548c max() \u51fd\u6570\u76f4\u63a5\u5728\u5b50\u67e5\u8be2\u4e2d\u83b7\u53d6\u6700\u5927\u8ddf\u8e2a\u53f7\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>\u5982\u679c\u4e3b\u952e\u4f4d\u4e8e b \u8868\u4e2d\uff0c\u6211\u4eec\u8fd8\u53ef\u4ee5\u4f7f\u7528\u4ee5\u4e0b\u67e5\u8be2\uff1a<\/p>\n<pre>SELECT\n    a.*,\n    b.tracking_number,\n    b.is_cancel \nFROM a\nLEFT JOIN b ON a.sid = b.sid\nWHERE b.id IN (\n    SELECT MAX(id) FROM b GROUP BY sid\n);<\/pre>\n<p>\u6b64\u67e5\u8be2\u5c06\u9009\u62e9 a \u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u4ee5\u53ca\u6765\u81ea b \u8868\u7684\u8ddf\u8e2a\u53f7\u548c\u53d6\u6d88\u6807\u5fd7\uff0c\u5176\u4e2d id \u662f b \u8868\u4e2d\u7684\u6700\u5927 id\u3002<\/p>\n<p>\u672c\u7bc7\u5173\u4e8e\u300aSQL \u67e5\u8be2\u6c42\u52a9\uff1a\u5982\u4f55\u4ece\u4e24\u5f20\u8868\u4e2d\u83b7\u53d6\u552f\u4e00\u7ed3\u679c\uff1f\u300b\u7684\u4ecb\u7ecd\u5c31\u5230\u6b64\u7ed3\u675f\u5566\uff0c\u4f46\u662f\u5b66\u65e0\u6b62\u5883\uff0c\u60f3\u8981\u4e86\u89e3\u5b66\u4e60\u66f4\u591a\u5173\u4e8e\u6570\u636e\u5e93\u7684\u76f8\u5173\u77e5\u8bc6\uff0c\u8bf7\u5173\u6ce8\u4e3b\u673a\u5b9d\u8d1d\u516c\u4f17\u53f7\uff01<\/p>\n<dl>\n<dt>\n <\/dt>\n<\/dl>\n","protected":false},"excerpt":{"rendered":"<p>SQL \u67e5\u8be2\u6c42\u52a9\uff1a\u5982\u4f55\u4ece\u4e24\u5f20\u8868\u4e2d&#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-201002","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/201002","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=201002"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/201002\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=201002"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=201002"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=201002"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}