如何在一条SQL语句中设定不同的查询条件？

[angelcool]

表a有如下三个字段：
OrgID Flag Type

需要获得满足：
1、A1 = Flag为1的所有OrgID的总量；
2、A2 = Type为2的所有OrgID的总量；

最终要得到A3= A1/A2；



如何用一条语句实现？？

[jwdream2008]

select A3=(select count(1) from a where Flag=1)/(select count(1) from a where Type=2) from a

[angelcool]

怎么得到了一堆零？？

[zhousq00]

Select case Flag When 1 Then Count(OrgID) End case as A1/Case Type When 2 Then Count(OrgID) End case As A2 From a

[angelcool]

而且得到的结果不是一个数值，而是很多行数据，并且都是零。

？？？

[TheGodOfGods]

去掉后边from a 就不会有多列了
结果为零是运算“/”的问题
SELECT A3 = 3/4
/*
A3
0
*/

[TheGodOfGods]

if object_id('a') IS NOT NULL
	drop table a
create table a(OrgID [int] IDENTITY(1,1) NOT NULL, Flag int,Type int)
insert into a
select 1, 1 union all
select 1, 2 union all
select 1, 3 union all
select 2, 2 union all
select 3, 2 union all
select 4, 2

--期望结果
--A1 = 3 A2 = 4 
--A3 = 3/4 = 0
select A3=(select count(1) from a where Flag=1)/(select count(1) from a where Type=2)
/*
A3
-----------
0
(1 行受影响)
*/
select A3=(select count(1) from a where Flag=1)%(select count(1) from a where Type=2)
/*
A3
-----------
3
(1 行受影响)
*/

[xiaoliaoyun]

SELECT A1 = SUM(CASE WHEN Flag = 1 THEN OrgID END)
      ,A2 = SUM(CASE WHEN Type = 2 THEN OrgID END)
      ,A3 = CASE WHEN SUM(CASE WHEN Type = 2 THEN OrgID END) = 0 THEN 0
                 ELSE SUM(CASE WHEN Flag = 1 THEN OrgID END)* 1.0 
                     /SUM(CASE WHEN Type = 2 THEN OrgID END) END
FROM A

[hello926]

SELECT A1=SUM(CASE flag when 1 then orgid end),
A2=SUM(CASE flag when 2 then orgid end),
A3=SUM(CASE flag when 1 then orgid end)/SUM(CASE flag when 2 then orgid end)
from tb

[angelcool]

请大侠帮帮忙呀

[修改一下昵称]

select cast((cast(3 as numeric(18,2))/cast(4 as numeric(18,2))) as numeric(18,2)) as f
/*
f
---------------------------------------
0.75

(1 行受影响)
*/

[angelcool]

问题中描述的查询条件只设定一个字段作为查询条件，是为了描述问题，实际上的查询条件涉及多个字段。

所以应该无法使用CASE。

请大侠帮忙！

[angelcool]

declare @A3 Float

select A3=(select count(1) from a where Flag=1)*100
/(select count(1) from a where Type=2)

这样可以得到一个整数结果，但实际上应该是一个小数值才对。

有其他函数或者其他除法表达式？

还是我的变量定义不对？