A colleague of mine used a technique in a multiple database report that works, but that he cannot adequately explain to me. I’m hoping someone here can shed some light on this one. In the following description, tables A and B are in different databases. The report acquires a list of invalid IDs from table B and uses these to filter (exclude) information drawn from table A. The report first defines a formula “X” as follows.

IF {A.ID1} = {B.ID2} THEN “Y” ELSE “N”

Then in the record selection formula we fine the following.

IF {@X} <> “Y” THEN “evaluate more selection criteria on table A columns”

This works, but I don’t understand why. It seems that some kind of iteration needs to happen when evaluating formula “X” for each A.ID1 value.