Question

我正在创建一个函数，所以我可以获取select语句的结果并将它们放在我们数据库的视图中。我的SELECT语句在运行时返回一个结果，但是当我将它放入创建函数时，我得到错误：

Only one expression can be specified in the select list when the 
subquery is not introduced with EXISTS.

我仍然是新人并且正在学习，并且会感谢我在做错的任何帮助。

CREATE FUNCTION CXi_Application 

@Application nvarchar(255), @Wave nvarchar(255)

RETURNS int
AS
BEGIN

DECLARE @Return int


SET @Return = 
(SELECT @Application, (
(sum(CASE WHEN overall_score IN (1) THEN 1 ELSE 0 END) + sum(CASE WHEN effective_score IN (1) THEN 1 ELSE 0 END) + sum(CASE WHEN easeuse_score IN (1) THEN 1 ELSE 0 END)) + 
(sum(CASE WHEN overall_score IN (2) THEN 2 ELSE 0 END) + sum(CASE WHEN effective_score IN (2) THEN 2 ELSE 0 END) + sum(CASE WHEN easeuse_score IN (2) THEN 2 ELSE 0 END)) + 
(sum(CASE WHEN overall_score IN (3) THEN 3 ELSE 0 END) + sum(CASE WHEN effective_score IN (3) THEN 3 ELSE 0 END) + sum(CASE WHEN easeuse_score IN (3) THEN 3 ELSE 0 END)) + 
(sum(CASE WHEN overall_score IN (4) THEN 4 ELSE 0 END) + sum(CASE WHEN effective_score IN (4) THEN 4 ELSE 0 END) + sum(CASE WHEN easeuse_score IN (4) THEN 4 ELSE 0 END)) + 
(sum(CASE WHEN overall_score IN (5) THEN 5 ELSE 0 END) + sum(CASE WHEN effective_score IN (5) THEN 5 ELSE 0 END) + sum(CASE WHEN easeuse_score IN (5) THEN 5 ELSE 0 END)))/
(count(overall_score) + count(effective_score) + count(easeuse_score) * 1.00 )
FROM FY14_DataMerge
WHERE [Status] = 'Completed' AND [Application] = @Application AND [Wave] = @Wave);

-- Return the result of the function
RETURN @Return

END
GO

Answer 1

您已在DDL中指定您希望该函数返回INT

RETURNS int

但是，您的结果集包含@Application和计算本身。基本上，您已声明您正在创建标量值函数，但您的代码正在尝试返回表值结果。首先，您需要确定您想要实际执行的操作。

如果你要返回一个结果（通常在调用语句的SELECT部分中找到），那么你很可能正在寻找一个标量值函数，你需要删除{{1}从函数DDL中的@Application语句调用。

如果您确实想要从函数返回的值，那么您将需要一个表值函数。此外，这是一个非常简单的查询，因此您可以将其设为具有definite performance benefits的内联TVF，但我不确定它们在您的情况下会有多清楚。

以下是制作内联TVF的样子：

SELECT

但是，如果5是每个数据点的最大值，那么为什么不重构为：

CREATE FUNCTION CXi_Application 

@Application nvarchar(255), @Wave nvarchar(255)

RETURNS TABLE
AS
RETURN SELECT @Application as [Application], (
(sum(CASE overall_score WHEN 1 THEN 1 ELSE 0 END) 
    + sum(CASE effective_score WHEN 1 THEN 1 ELSE 0 END) 
    + sum(CASE easeuse_score WHEN 1 THEN 1 ELSE 0 END)) 
    + 
(sum(CASE overall_score WHEN 2 THEN 2 ELSE 0 END) 
    + sum(CASE effective_score WHEN 2 THEN 2 ELSE 0 END) 
    + sum(CASE easeuse_score WHEN 2 THEN 2 ELSE 0 END)) 
    + 
(sum(CASE overall_score WHEN 3 THEN 3 ELSE 0 END) 
    + sum(CASE effective_score WHEN 3  THEN 3 ELSE 0 END) 
    + sum(CASE easeuse_score WHEN 3 THEN 3 ELSE 0 END)) 
    + 
(sum(CASE overall_score WHEN 4 THEN 4 ELSE 0 END) 
    + sum(CASE effective_score WHEN 4 THEN 4 ELSE 0 END) 
    + sum(CASE easeuse_score WHEN 4 THEN 4 ELSE 0 END)) 
    + 
(sum(CASE overall_score WHEN 5 THEN 5 ELSE 0 END) 
    + sum(CASE effective_score WHEN 5 THEN 5 ELSE 0 END) 
    + sum(CASE easeuse_score WHEN 5 THEN 5 ELSE 0 END))) 
/
(count(overall_score) + count(effective_score) 
    + count(easeuse_score) * 1.00 ) as CalcMetric
FROM FY14_DataMerge
WHERE [Status] = 'Completed' AND [Application] = @Application AND [Wave] = @Wave;
GO

创建函数SQL Server 2012时出错

1 个答案: