在SQL Server中选择2个不同的计数

Question

我需要从具有几列（数字，颜色等）的表中选择前20000，并且我需要在一个查询中从这些20000中获取红色的计数和蓝色的计数。

我知道如果我在临时表中插入前20000，然后从临时表中选择红色的计数，然后从临时表中选择蓝色的计数，我就能得到我想要的东西，但是我需要在一个查询中进行操作。

我尝试了下面，但它给了我每个数字的计数，我需要总数。

SELECT  top 20000 [number], count(color)
FROM [profile]
group by number
having color='red'

输出：

颜色| 计数

红色| 15000

蓝色| 5000

Answer 1

您可以使用iif ：

select  top 20000 [number]
     , sum(iif([color] = 'red', 1, 0) as red_count
     , sum(iif([color] = 'blue', 1, 0) as blue_count
from [profile]
group by [number]

或case ：

select  top 20000 [number]
     , sum(case when [color] = 'red' then 1 else 0 end) as red_count
     , sum(case when [color] = 'blue' then 1 else 0 end) as blue_count
from [profile]
group by [number]

编辑 。 更新问题后，我想您的查询应如下所示：

select t.[color]
     , count(t.[color])
from (select  top 20000 [color] from [profile]) t
group by t.[color]

Answer 2

您可以使用嵌套查询：

select inner.color, count(*) from 
(select top 20000 [number], color from [profile]) inner
group by inner.color

Answer 3

SELECT  top 20000 [number], count(color) as count_total, 
        sum(case when color='red' then 1 else 0 end) as count_red, 
        sum(case when color='blue' then 1 else 0 end) as count_blue
FROM [profile]
group by number