SQL案例 - 使用SELECT

Question

我在使用select语句在CASE语句中设置返回值时遇到问题......有人可以请看看吗？

DECLARE @SystemTypeId int 
SELECT @SystemTypeId = [SystemTypeId] FROM [Properties] WHERE [Id] = @PropertyId 

SET @RETURN_VAL = 
    CASE @SystemTypeId 
     WHEN 2 THEN (SELECT [Created] FROM [Assets] WHERE [Id] = @AssetId) 
     WHEN 3 THEN (SELECT dbo.GetAssetValueById([CreatedBy]) 
        FROM [Assets] 
        WHERE [Id] = @AssetId) 
     WHEN 9 THEN (SELECT [LastModified] 
        FROM [Assets] 
        WHERE [Id] = @AssetId) 
     ELSE NULL 
    END 

Answer 1

试试这个：

SELECT @RETURN_VAL = 
     CASE @SystemTypeId 
      WHEN 2 THEN [Created] 
      WHEN 3 THEN dbo.GetAssetValueById([CreatedBy]) 
      WHEN 9 THEN [LastModified] 
      ELSE NULL 
     END 
FROM [Assets] 
WHERE [Id] = @AssetId