OK, I am following you so far...
...I am presuming then that the Session Variable containing the UserID needs to be inputed into the database using data assist for each entry...
...I have found the session variable part of the data assist wizard, the column that is selected is id, but in the database is an incremental number as the record id as opposed to the user id.
So I guess I need to create another column in the database, UserID, so what do I put in the Store as: field? its currently set to WADA_Insert_xx