If/Then in Access query

Question

I need some help constructing an If/Then query in Access. I want the New Comments field to populate based on the Cardholder, Approver, and Reconciler columns:

If only Cardholder is filled: New Comments field = A
If only Reconciler is filled: New Comments field = B
If only Approver is filled: New Comments field = C
If Cardholder & Reconciler filled:  New Comments field =D
If Cardholder & Approver filled: New Comments field = E
If Cardholder & Reconciler & Approver filled: New Comments field = F
If Reconciler & Approver filled: New Comments field = G

Can you help?

Answer 1

In MS-Access, switch is the simpler way to handle multiple conditions:

select . . .
       switch([Cardholder] Is Not Null And [Reconciler] Is Not Null And [Approver] Is Not Null, "F",
              [Cardholder] Is Not Null And [Reconciler] Is Not Null, "D",
              [Cardholder] Is Not Null And [Approver] Is Not Null, "E",
              [Reconciler] Is Not Null And [Approver] Is Not Null, "G",
              [Cardholder] Is Not Null, "A",
              [Reconciler] Is Not Null, "B",
              [Approver] Is Not Null, "C",
              1=1, "H"
             )

Answer 2

Since you have three fields, and each may be either Null or Not Null there are 2 ³ = 8 possible cases.

The following will account for each:

NewComments: 
IIf([Cardholder] Is Not Null And [Reconciler] Is Not Null And [Approver] Is Not Null,"F",
    IIf([Cardholder] Is Not Null And [Reconciler] Is Not Null,"D",
        IIf([Cardholder] Is Not Null And [Approver] Is Not Null,"E",
            IIf([Reconciler] Is Not Null And [Approver] Is Not Null,"G",
                IIf([Cardholder] Is Not Null,"A",
                    IIf([Reconciler] Is Not Null,"B",
                        IIf([Approver] Is Not Null,"C",
                            "H"
                        )
                    )
                )
            )
        )
    )
)

The final result "H" corresponds to the case in which all three fields are Null .

The logic could obviously be reversed to remove the Not from each statement, but I've constructed the statement based on the example you provided.