mysql sql语句 查询文章表，评论表（根据评论表文章评论次数排序查询出文章count（），group，left join）
需求：
表1，文章表，
表2，评论表，
第一种实现方式：
SELECT a.id,a.title,a.content,a.type_id,count(b.id) as d from message as a LEFT JOIN comment as b on a.id=b.id GROUP BY b.id ORDER BY d desc
第二种实现方式：
SELECT a.id,a.title,a.content,a.type_id,if(ISNULL(c)=1,0,c) as d from message as a LEFT JOIN
(SELECT id,count(id) as c from comment GROUP BY id) as b
on a.id=b.id ORDER BY c desc
(SELECT id,count(id) as c from comment GROUP BY id) as b
on a.id=b.id ORDER BY c desc
结果：