如果條件滿足，選擇參數

Question

如果滿足條件，我想選擇特定的元素。請看下面我的代碼。我如何選擇CASE子句中的數據？我的辦法不起作用

CREATE PROCEDURE [dbo].[GetUsers] 
@firstName varchar(100) = '', 
@isCounterSelected int, 
@countries dbo.tvp_stringArray READONLY 
AS 

BEGIN 
    SET NOCOUNT ON; 

SELECT [PK_UserID] AS Id 
     ,[UserNickName] 
     ,[description] 
     ,CASE 
     WHEN @isCounterSelected = 1 THEN (NULL AS MCount, NULL AS GCount, NULL AS CCount) 
     ELSE '' 
     END 
     FROM [dbo].[User_Existing]  
     WHERE (@firstName NOT LIKE '' AND firstName LIKE @firstName + '%') 
     AND Country IN (SELECT inputValue FROM @countries) 

Answer 1

我認爲這將是有語法錯誤固定：

CREATE PROCEDURE [dbo].[GetUsers] 
@firstName varchar(100) = '', 
@isCounterSelected int, 
@countries dbo.tvp_stringArray READONLY 
AS 

BEGIN 
    SET NOCOUNT ON; 

SELECT [PK_UserID] AS Id 
     ,[UserNickName] 
     ,[description] 
     ,CASE 
     WHEN @isCounterSelected = 1 THEN NULL 
     ELSE '' 
     END AS MCount 
     ,CASE 
     WHEN @isCounterSelected = 1 THEN NULL 
     ELSE '' 
     END AS GCount 
     ,CASE 
     WHEN @isCounterSelected = 1 THEN NULL AS CCount 
     ELSE '' 
     END AS CCount 
     FROM [dbo].[User_Existing]  
     WHERE (@firstName NOT LIKE '' AND firstName LIKE @firstName + '%') 
     AND Country IN (SELECT inputValue FROM @countries) 
END