请教一条SQL server 语句.

selct t1.id,t1.username, count(*) from t1 inner join t2 on t1.id=t2.userid group by t2.userid
其中
t1.id=用户信息表中的用户编号
t2.userid=用户文章表中的用户编号

select * from fk a ,pk b where a.id=b.id

select a.id, a.[username],count(a.id) as num from 主键表 a,外键表 b where a.id=b.id group by a.id,a.[username]

select count(*) from idpk,idfk where pk=fk

select A.[用户名],count(B.ID) as [发表数量] from [用户信息] A,[用户发表文章] B
where A.ID=B.ID
group by A.[用户名]