Yeah, I tried filtering out NULL with no luck. How would I say if it contains a space?
UPDATE Users INNER JOIN UserIdInfo on Mid(Users.ID, (InstrRev(Users.ID, " ") + 1)) = UserIdInfo.OldUserId
SET Users.ID = Mid(Users.ID, 1, (InstrRev(Users.Id, " "))) & [UserIdInfo].[NewUserId] WHERE Users.ID...