SQL SUM CASE語句

Question

我：

SUM 
(
case 
when LC.[DWC] = 0 and LC.BI = 1 then 1 
else LC.[DWC] END AS DC 
) 
AS [DWC] 

但我收到錯誤消息：

'SUM' 是無法識別的內置函數名稱。

我該如何解決這個問題？

Answer 1

假設你使用的是SQL服務器：

Select SUM(CASE WHEN (LC.[DWC] = 0 and LC.BI = 1) THEN 1 ELSE LC.[DWC] END) AS [DWC] 
FROM LC