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
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
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