>I used Helen's previous suggestion created a view and then did a join
>on the view and the lookup table. It solves my problem.

Why use a view for this? Simply do a

select tablename, weight
from replication_order ro
where exists (select 1 from replication_log rl where rl.tablename =
ro.tablename)
order by 2

This should get you what you appear to want pretty quickly.

HTH,
Set