On 9 May 2017 at 09:56, Patrick B <patrickbakerbr@xxxxxxxxx> wrote: > Hi guys, > > I have two tables that supports the same data, but different table DDL (We > are migrating all the data from one to another). > > What I need is basically: > > 1. Query looks for the data on table A, > 2. if it doesn't find it on table A, go look for it on table B > > Now, how could I do that in a Select? Can you please provide some examples? > > > I'm using PostgreSQL 9.1. You could exploit DISTINCT ON for this. Something like: select distinct on (id) id,value from (select *,'a' tablename from a where id=1 union all select *,'b' tablename from b where id=1) ab order by id,tablename; Assuming that id is what you want to be unique. -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
