求大神帮忙看看怎么写这条sql语句，毕设遇到瓶颈了
问题描述：
这是我的论坛的帖子信息表
create table tiezi
(
tieziid int not null primary key identity(1,1),
userid int ,
tztitle varchar(20) not null,
tzcontent varchar(200)not null,
tztime datetime not null,
tztop varchar(1),
hfnum int
)
这是帖子的回复表
create table tzpinglun
(
pinglunid int not null primary key identity(1,1),
tieziid int not null,
tzpluserid int ,
tzplcontent varchar(200),
tzpltime datetime,
tzpltitle varchar(20)
)
如何能够查询出第一章表的所有内容同时连接第二章表查出回复数，这两张表用tieziid相连
答
SELECT A.*,(select count(*) from tzpinglun where tieziid =A.tieziid ) as 回复数 FROM tiezi A
答
select a.*,b.num from tiezi a left join
(select tieziid, count(tieziid) as num from tzpinglun group by tieziid) b
on a.tieziid = b.tieziid