sql语句，同张表内，两个字段A,B，条件是查出b中多个数据符合a字段的值

库名
a b
a 0
a 1
b 0
c 1
d 0
d 1
需要查出同时有0和1 下a字段的值,我并不知道A表
结果是：
a 0
a 1
d 0
d 1

select *
  from 表
 where a in (select a
               from 表
              where b in (0, 1)
              group by a
             having count(distinct b) = 2)

where条件b=0 and b =1，group by 过滤有相同的值这样吗

select a from
(
select * from 表 a where b in (0,1)
)
having count(b)=2