Quic question - Field verification on a Form

[luis.a.roman]

I have a form that I need to update a field depending on the previous
value of that field. Because I have the field in the form with the new
value. is there any away that I can check the field value prior to the
change?

I would like to read the table and retrieve the field and check value.
But not able to figure out how to do that?

Suggestions please . I'm stuck.