再套一层:select COUNT(1)from (select a.col1
from (select '11' col1 from dual
union all
select '22' from dual
union all
select '33' from dual
union all
select '11' from dual
union all
select '33' from dual
union all
select '22' from dual
union all
select '33' from dual
union all
select '11' from dual) a
group by a.col1) t