Hi Ulises.

>> However, the line
If BARCODE = .NULL.
doesn't evaluate as true. Why? <<

One of the best explanations that I heard for this was given by Tamar Granor in a session on SQL back in 1997. She said that you can think of .NULL. as meaning 'I don't know'. So, if you say:

Does "I don't know" equal "I don't know"

The answer would have to be "I don't know"

That's why you should use ISNULL() to check for whether or not something is NULL.

Marcia