求一条SQL语句，请大家帮忙,该怎么解决

求一条SQL语句，请大家帮忙
有一张表，其中有字段A1，B1
A1不会有重复列，B1有重复列

例如
A1 B1
----------------
A AA1
B AA2
C AA2
D AA3

想写一条SQL语句，把所有B1字段重复的记录都选出来
结果
B AA2
C AA2




[解决办法]

SQL code

select *from tb twhere exists (select 1 from tb where B1 = t.B1 and A1 <> t.A1)
[解决办法]
SQL code
select * from tb t where exists (select 1 from tb where B1 = t.B1 and A1 <> t.A1)
[解决办法]
SQL code
select * from tb t where exists (select 1 from tb where B1 = t.B1 and A1 <> t.A1)--或者select * from tb where B1 in (select B1 from tb group by B1 having count(B1)>1)