求助一条SQL查询

[carkiller]

表1
UserID UserName
1 AAA
2 BBB
3 CCC

表2
ID ServicingID
1 2
2 2
3 3

表1的UserID和表2的ServicingID是对应的，现在想检索出表1的UserName
条件是表2里面对应ServicingID内值相同个数小于2个的对应表1的那个UserName

这个该怎么写？谢谢大家了~

[ice_frank]

select a.UserName,count(1) num from 表2 a
inner join 表1 b on a.ServicingID=b.UserID
group by a.UserName,b.ServicingID
where num<2

[fengjiafeng1984]

[Quote=引用 1 楼 ice_frank 的回复:]
select a.UserName,count(1) num from 表2 a
inner join 表1 b on a.ServicingID=b.UserID
group by a.UserName,b.ServicingID
where num <2
[/Quote]

[银狐被占用]

select 表1.username,表2.servicingid,count(*) from 表1 left join 表2 on 表1.userid=表2.servicingid
group by 表1.username,表2.servicingid having count(*)<2

[ivmyzj]

[Quote=引用 1 楼 ice_frank 的回复:]
select a.UserName,count(1) num  from 表2 a
inner join 表1 b on a.ServicingID=b.UserID
group by  a.UserName,b.ServicingID
where num <2
[/Quote]

[叶子]

select a.UserName,count(1) num from 表2 a
inner join 表1 b on a.ServicingID=b.UserID
group by a.UserName,b.ServicingID
where num <2

[xiaolukatie]

[Quote=引用 3 楼 baby97 的回复:]
select 表1.username,表2.servicingid,count(*) from 表1 left join 表2 on 表1.userid=表2.servicingid
group by 表1.username,表2.servicingid having count(*) <2
[/Quote]

用having

[zhong2006]

select a.UserName,count(*) num from 表2 a inner join 表1 b on a.ServicingID=b.UserID group by a.UserName,b.ServicingID where num <2

[wxg22526451]

select a.username from @t1 a left join @t2 b on a.userid=b.ServicingID
group by a.username having count(b.ServicingID)<2