选择具有不同值的相同列的计数

Question

我有这样的选择：

SELECT 
    [Status] AS Requested
    ,[Status] AS [Sent]
    ,[Status] AS Finished
     FROM Store.[Order] 

Status是一个int值，我想要Count all Status

1. 计算值= 1并显示为请求值。
2. 计数值= 2并显示为已发送。
3. 计数值= 3并显示为已完成。

我怎样才能实现它？此致

Answer 1

使用case表达式根据值（ 1,2,3 ）计算状态

SELECT 
       SUM(CASE WHEN [Status] = 1 THEN 1 ELSE 0 END) AS Requested,
       SUM(CASE WHEN [Status] = 2 THEN 1 ELSE 0 END) AS Sent,
       SUM(CASE WHEN [Status] = 3 THEN 1 ELSE 0 END) AS Finished
FROM Store.[Order]