help with access query

i have table MyTbl that contain date1, date2, date3

if date1=null i need that in field memo will be 'A'

elae if date2=null i need that in field memo will be 'B'

else if date3=null i need that in field memo开发者_如何学C will be 'C'

is it can made on access 2007 in query ?

thank's in advance

---

If I understand correctly, you should be able to do this with using IIF -

memo: IIf(IsNull([date1]=True),"A",IIf(IsNull([date2])=True,"B",IIf(IsNull([date3])=True,"C")))