if a number in column is negative,show positive,else show the number

Question

I have a [Preko]column in a query that is calculating the difference between two columns.If the number is negative,I need to show it positive,and if it is positive,it should stay the same.I can't use ABS in this one.I tried with the case,but it didn't work. The problem I am getting is that column Preko is invalid.

This is the code for my second try with iif:

SELECT FP.Firma
      ,FP.NazFirme
      ,FP.Konto
      ,FP.NazivKonta
      ,FP.Partner
      ,FP.NazivPartnera
      ,Sum(FP.Duguje) AS dug
      ,Sum(FP.Potrazuje) AS pot
      ,Sum(IIf([FP].[Konto] Like '2*'
      ,[duguje]-[potrazuje]
      ,[potrazuje]-[duguje])) AS USaldo
      ,Sum(IIf([datumval]<= '1.1.2017'
      ,IIf([FP].[Konto] Like '2*'
      ,[duguje]-[potrazuje]
      ,[potrazuje]-[duguje]),0)) AS [Preko]
      ,IIf([Preko]<0,0,[Preko]) AS Preko1
FROM tblFinansijskiPodaci FP
Where FP.Firma = 1 
AND FP.Partner=1110
GROUP BY FP.Firma
        ,FP.NazFirme
        ,FP.Konto
        ,FP.NazivKonta,
        ,FP.Partner
        ,FP.NazivPartnera 
HAVING (((FP.Konto)=2040))

Answer 1

You can also use a case statement instead of the iif section.

  CASE WHEN Preko<0 THEN 0 ELSE Preko END

or

  CASE WHEN Preko<0 THEN -Preko ELSE Preko END

That seems to be more in line with your logic depending on how you want to handle the negatives.