{"id":6796,"date":"2024-11-14T12:46:56","date_gmt":"2024-11-14T04:46:56","guid":{"rendered":"https:\/\/fwq.ai\/blog\/6796\/"},"modified":"2024-11-14T12:46:56","modified_gmt":"2024-11-14T04:46:56","slug":"%e5%a6%82%e4%bd%95%e5%90%88%e5%b9%b6-count-group-by-%e5%92%8c-select-%e8%af%ad%e5%8f%a5%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/fwq.ai\/blog\/6796\/","title":{"rendered":"\u5982\u4f55\u5408\u5e76 COUNT GROUP BY \u548c SELECT \u8bed\u53e5\uff1f"},"content":{"rendered":"<p><img decoding=\"async\" src=\"https:\/\/img.php.cn\/upload\/article\/001\/246\/273\/172993231282695.jpg\" class=\"aligncenter\" title=\"\u5982\u4f55\u5408\u5e76 COUNT GROUP BY \u548c SELECT \u8bed\u53e5\uff1f\u63d2\u56fe\" alt=\"\u5982\u4f55\u5408\u5e76 COUNT GROUP BY \u548c SELECT \u8bed\u53e5\uff1f\u63d2\u56fe\" \/><\/p>\n<p><strong>\u5408\u5e76 count group by \u548c select \u8bed\u53e5<\/strong><\/p>\n<p>\u5728\u5bf9\u540c\u4e00\u5f20\u8868\u540c\u65f6\u6267\u884c count group by \u548c select \u64cd\u4f5c\u65f6\uff0c\u53ef\u4ee5\u8003\u8651\u4ee5\u4e0b\u5408\u5e76\u8bed\u53e5\u7684\u65b9\u6cd5\uff1a<\/p>\n<p><strong>\u5408\u5e76 select \u548c count \u8bed\u53e5<\/strong><\/p>\n<p>\u53ef\u4ee5\u4f7f\u7528 select \u5b50\u53e5\u540c\u65f6\u83b7\u53d6\u6570\u636e\u548c\u8ba1\u6570\uff1a<\/p>\n<pre>select t1.a, t1.b, count(*) as count from test as t1 group by t1.a, t1.b<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p>\u8fd9\u5c06\u4ea7\u751f\u4e00\u7ec4\u65b0\u7684\u8bb0\u5f55\uff0c\u5176\u4e2d\u5305\u542b\u539f\u59cb\u8868\u4e2d\u7684\u5217\u4ee5\u53ca\u7528\u4e8e\u5206\u7ec4\u7684\u5217\u7684\u8ba1\u6570\u3002<\/p>\n<p><strong>\u5408\u5e76 left join<\/strong><\/p>\n<p>\u53e6\u4e00\u79cd\u65b9\u6cd5\u662f\u6267\u884c left join\uff0c\u5c06\u539f\u59cb\u8868\u4e0e\u5206\u7ec4\u8868\u8054\u7cfb\u8d77\u6765\uff1a<\/p>\n<pre>select t1.a, t1.b, t2.count from test as t1\nleft join (\n    select a, b, count(*) as count\n    from test\n    group by a, b\n) as t2 on t1.a = t2.a and t1.b = t2.b<\/pre>\n<p>  \u767b\u5f55\u540e\u590d\u5236   <\/p>\n<p>left join \u5c06\u786e\u4fdd\u6240\u6709\u539f\u59cb\u884c\u90fd\u5305\u542b\u5728\u5176\u7ed3\u679c\u96c6\u4e2d\uff0c\u5176\u4e2d\u6765\u81ea\u5206\u7ec4\u8868\u7684\u8ba1\u6570\u5c06\u9644\u52a0\u5230\u5177\u6709\u5339\u914d\u5217\u503c\u7684\u884c\u7684\u672b\u5c3e\u3002<\/p>\n<p>\u4ee5\u4e0a\u5c31\u662f\u5982\u4f55\u5408\u5e76 COUNT GROUP BY \u548c SELECT \u8bed\u53e5\uff1f\u7684\u8be6\u7ec6\u5185\u5bb9\uff0c\u66f4\u591a\u8bf7\u5173\u6ce8\u7c73\u4e91\u7f51\u5176\u5b83\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5408\u5e76 count group by \u548c select \u8bed\u53e5 \u5728\u5bf9\u540c\u4e00\u5f20\u8868\u540c\u65f6\u6267\u884c count group by \u548c select \u64cd\u4f5c\u65f6\uff0c\u53ef\u4ee5\u8003\u8651\u4ee5\u4e0b\u5408\u5e76\u8bed\u53e5\u7684\u65b9\u6cd5\uff1a \u5408\u5e76 select \u548c count \u8bed\u53e5 \u53ef\u4ee5\u4f7f\u7528 select \u5b50\u53e5\u540c\u65f6\u83b7\u53d6\u6570\u636e\u548c\u8ba1\u6570\uff1a select t1.a, t1.b, count(*) as count from test as t1 group by t1.a, t1.b \u767b\u5f55\u540e\u590d\u5236 \u8fd9\u5c06\u4ea7\u751f\u4e00\u7ec4\u65b0\u7684\u8bb0\u5f55\uff0c\u5176\u4e2d\u5305\u542b\u539f\u59cb\u8868\u4e2d\u7684\u5217\u4ee5\u53ca\u7528\u4e8e\u5206\u7ec4\u7684\u5217\u7684\u8ba1\u6570\u3002 \u5408\u5e76 left join \u53e6\u4e00\u79cd\u65b9\u6cd5\u662f\u6267\u884c left join\uff0c\u5c06\u539f\u59cb\u8868\u4e0e\u5206\u7ec4\u8868\u8054\u7cfb\u8d77\u6765\uff1a select t1.a, t1.b, t2.count from test as t1 left join ( [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-6796","post","type-post","status-publish","format-standard","hentry","category-16"],"_links":{"self":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/6796","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/comments?post=6796"}],"version-history":[{"count":0,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/posts\/6796\/revisions"}],"wp:attachment":[{"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/media?parent=6796"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/categories?post=6796"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fwq.ai\/blog\/wp-json\/wp\/v2\/tags?post=6796"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}