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

Pandu Poluan, 12.12.2011 05:39:
> Hello!
>
> Due to some legacy apps, I end up with two tables with similar information, but with zero intersection (i.e., both
tablesare exclusive of each other). 
>
> For illustration:
>
> table_one has the fields emp_id and fullname
>
> table_two has the fields employee_id, first_name, and last_name
>
> Now, I need a query that will search for employee ID in both tables and return his/her full name.
>
> How do I do that? Will a simple UNION suffice?

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