求一SQL查询，困扰好多天了,该如何解决_Sql Server

求一SQL查询，困扰好多天了
@a=sum(t1.c1)
@b=sum(CASE WHEN t2.d= 1
THEN t2.e
ELSE t2.e/100 * @a)
t1.f=t2.f
求@a-@b的SQL，大虾帮忙啊，小弟感激不尽

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select @[email protected]
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把表给出来
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SQL code

select    @a=sum(t1.c1),    @b=sum(CASE WHEN t2.d= 1 THEN t2.e ELSE t2.e/100 [email protected] end),    @[email protected]from    t1,t2where     t1.f=t2.f
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SQL codedeclare @a as intselect @a = sum(t1.c1) from t1declare @b as intselect @b = sum(CASE WHEN t2.d = 1 THEN t2.e ELSE t2.e/100 * @a) from t1 , t2 where t1.f=t2.f select @a - @b
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SQL codedeclare @a decimal(10,2),@b decimal(10,2)select @a=sum(c1) from t1select @b=sum(CASE WHEN t2.d= 1 THEN t2.e ELSE t2.e/100 * @a end) from t1,t2 where t1.f=t2.fselect @[email protected]
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我在4楼的是返回一个值.
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sum只返回1行阿，你没有group，返回什么列
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关注，学习！
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看不懂
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..
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