Reporting Services Divide by Zero Error in Report Expression

It’s a real pain – if I have a field that I want to calculate as one field divided by another, I have found that I get a divide by zero error when one of the fields is 0.

Normally, I would do a quick check on the field I am dividing by (the divisor) before using it in a calculation. In a field expression, the only way to include this kind of check is with an inline if statement. So I would have something like this in my report expression:

=IIF(Fields!Budget.Value = 0, "", Fields!Budget.Actual / Fields!Budget.Value)

But there is a problem with this. The False part of the IIF function still gets evaluated and your field shows #Error instead of a blank as expected.

There is a really simple way around this – create your own VB.NET function and call this from within the expression. Creating a VB.NET function is really easy as long as you are playing nicely in the sandbox (i.e. not trying to access any of the machine’s resources.) Here is a sample function that you can paste into the Code property of the report:

Public Shared Function VarPercent(ByVal Actual As Decimal, ByVal Budget As Decimal) As Decimal
If Budget = 0 Then
Return 0
End If
Return (Actual / Budget)
End Function

To use the function, just put the following in your expression:

=code.VarPercent(Fields!Actual.Value,Fields!Budget.Value)

That’s it!

If the divisor is 0, we return 0. We could of course return an empty string – although you can just as easily do this by formatting the field using a formatting expression that shows blank for zeros.