是这意思吗? with t as ( select 'a' as field from dual union all select 'b' from dual union all select 'c' from dual union all select 'd' from dual union all select 'e' from dual ) select field from ( select field,rownum as rn from t ) where rn <= 3FIELD ----- a b c
with t as (
select 'a' as field from dual
union all
select 'b' from dual
union all
select 'c' from dual
union all
select 'd' from dual
union all
select 'e' from dual
)
select field from (
select field,rownum as rn from t
) where rn <= 3FIELD
-----
a
b
c
一般要实现树形结构的查询一般都是用connect by prior