>I ran the following command on a table called PROPERTY:
>
>replace pr_addr1 with "" for pr_code = ""
>
>and it replaced every single record's pr_addr1 with a blank and there were no pr_codes = to "".

That's a risky way to do it - you can fiddle with SET EXACT and SET ANSI to see if that solves it. But it's easier just to use a function like EMPTY:

replace pr_addr1 with "" for EMPTY(pr_code) IN tablename