Cannot perform aggregate function on an expression

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Cannot perform aggregate function on an expression

Author

Topic

XULA95
Starting Member

2 Posts

Posted - 2011-10-26 : 15:06:03

I know there have been similar questions on this subject but I can't seem to find one that helps me. My SQL code is below...How can I rewrite the query below to not get the following error:

Cannot perform an aggregate function on an expression containing an aggregate or a subquery.

SELECT CAF.DBName,
SUM(CASE
WHEN CAF.Fee < 1
Then (Select C.MonthlyFee from Customers C where CAF.DBName = C.DBName)
ELSE
CAF.Fee
End)
FROM dbo.CustomerAdditionalFees CAF
WHERE (OneTimePaid IS NULL)
GROUP BY DBName

Sachin.Nand

2937 Posts

Posted - 2011-10-26 : 15:10:32

You cannot combine a SUM and a SELECT as a correlated sub query.

PBUH

XULA95
Starting Member

2 Posts

Posted - 2011-10-26 : 16:00:35

I actually figured it out myself with a bit more research. I am posting my fix for others who will likely have a similar problem.

SELECT DBName, SUM(Fees) AS Fee
FROM (SELECT DBName, CASE WHEN ABS(CAF.Fee) < 1 THEN
(SELECT C.MonthlyFee * CAF.Fee
FROM Customers C
WHERE CAF.DBName = C.DBName) ELSE CAF.Fee END AS Fees
FROM dbo.CustomerAdditionalFees AS CAF
WHERE (OneTimePaid IS NULL)) AS T
GROUP BY DBName

X002548
Not Just a Number

15586 Posts

Posted - 2011-10-26 : 16:09:28

..ummm...IF you say so...

WHEN ABS(CAF.Fee) < 1

....<cough>that's some good sheet man</cough>

Brett

8-)

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Lamprey
Master Smack Fu Yak Hacker

4614 Posts

Posted - 2011-10-26 : 16:31:57

You can get rid of the correlated sub-query if you like. Although, you might need a LEFT join depending on your actual data and expected results:

SELECT 
    CAF.DBName, 
    SUM
    (
        CASE 
            WHEN ABS(CAF.Fee) < 1 THEN
                C.MonthlyFee * CAF.Fee
            ELSE CAF.Fee 
        END 
    )AS Fees
FROM 
    dbo.CustomerAdditionalFees AS CAF
INNER JOIN        
    dbo.Customers AS C
    ON CAF.DBName = C.DBName        
WHERE 
    CAF.OneTimePaid IS NULL
GROUP BY 
    CAF.DBName

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