I have two tables with the same field lets call them a.flag and b.flag. I am making a join query of these two tables, and need to add a field that create an if.then.else criteria. If table a.flag is blank then b.flag else a.flag.
That is not my key joining fields. I have two tables and I join them by c,d and e. I just need a to come from one table or the other. Would I need to do that outside of query design?
The parameter prompt is Access telling you it can't find something (whatever is listed in the box). Double check your spellings. You can't take out the Expr1, but you can change it to something of your choosing. Thus in design view you'd have:
DesiredFieldName: Nz(a.Flag, b.Flag)
If you're still stuck, can you attach the db here?