Favorites In DB, Duplicity Checkup

I'm trying to give to my site's visitors an option of edding some records to the list of favorites. Favorites is a table in the DB, called fav_recs, with 3 fields: fav_id (auto number), rec_id, user_id. User can see his favs when entering the personal page (with user name and password), where there's a query that pulling the rec_id where user_id=session("user_id").

Now, when the user clicks a button "Add to favs" it goes to another page with the rec_id in the queryString. There it supposed to check whether this rec_id already presents in the RS where user_id = session("user_id") and if it does - to present a message saying that the user already has this record on his fav's list, and if it doesn't - to insert it into the table. I tried to do the following: Code: