1.博客% b& z, f( f; _" \3 D3 C
blogger_id1 232.帖子9 S# S% R+ N9 g5 u( P' Q
post_from_blogger_id1 11223如你所见,博主1发布的帖子比其他博主多,博主3发布的博文少。如何建立查询,选择所有博客,并根据帖子数量对其进行排序?7 R* M( F3 l$ T1 e; [
: x1 h4 z d3 ^9 a 解决方案: 7 O& l" Q `# S" e SELECT bloggers.*,COUNT(post_id) AS post_count FROM bloggers LEFT JOIN blogger_posts ON bloggers.blogger_id = blogger_posts.blogger_id GROUP BY bloggers.blogger_id ORDER BY post_count(注意:MySQL有了特殊的语法,你可以通过GROUP BY针对这种情况,不汇总所有值)。