我有如下的查询
select columns
from (select columns1
from result_set
where condition_common and condition1) as subset1
join
(select columns2
from result_set
where condition_common and condition2) as subset2
on subset1.somekey = subset2.somekey
我想以某种方式重用
select columns from result_set where condition_common
我以上的查询过于简单,但上述的选择在现实中是巨大而复杂的.我不想有确保两者都同步的负担
我没有任何方法以编程方式重用它. T-sql被排除.我只能写简单的查询.这是一个应用限制.
有没有办法在单个语句中重用同一个子查询
解决方法
如果您使用sql Server 2005,请使用
Common Table Expression(CTE)：
with cte as (
select columns
from result_set
where condition_common
)
select columns
from cte as subset1
join
cte as subset2
on subset1.somekey = subset2.somekey
where otherconditions
