Re: SELECT from two tables with different field names? - Mailing list pgsql-novice

Pandu Poluan, 13.12.2011 04:40:
>  > Yes a UNION should do (actually a UNION ALL as it will not try to remove duplicates which makes the query faster)
>  >
>  > select *
>  > from (
>  >   select emp_id, fullname
>  >   from table_one
>  >
>  >   union all
>  >
>  >   select employee_id,
>  >          first_name||' '||last_name
>  >   from table_two
>  > ) t
>  > where emp_id = 1
>  >
>
> Thank you! I can see how UNION ALL will speed the query.
>
> But, shouldn't I put the WHERE clause in the inner SELECTs?

I thought your goal was to just have a single condition. But if you can push that into the union that would be more
efficient.

Regards
Thomas