IIF used in Northwind query

[johngalt47]

I am totally lost with this usage of the IIF function. I can't figure out what is the truepart and what is the falsepart.

File As: IIf(IsNull([Last Name]),IIf(IsNull([First Name]),[Company],[First Name]),IIf(IsNull([First Name]),[Last Name],[Last Name] & ", " & [First Name]))

 

[sneuberg]

True
False

File As: IIf(IsNull([Last Name]),IIf(IsNull([First Name]),[Company],[First Name]),IIf(IsNull([First Name]),[Last Name],[Last Name] & ", " & [First Name]))

for the first IIf

 

[sneuberg]

Sometime it's also helpful to break these down into their equivalent functions where it's easier to see what they are doing. When I do that for this one I get,

Function GetName(LastName As Variant, FirstName As Variant, Company As Variant) As Variant

If IsNull(LastName) Then
     If IsNull(FirstName) Then
        GetName = Company
    Else
       GetName = FirstName
    End If
Else
    If IsNull(FirstName) Then
        GetName = LastName
    Else
        GetName = LastName & ", " & FirstName
    End If
End If

End Function