Re: SQL query question

> Hi all,
>
> I have 2 tables, with a 1-n relation:
>
> parent( oid, parent_name)
> child(oid, child_name, iod_parent)
>
> How do I get the parent_names of all parents without a child?

select parent_name from parent
  left join child on (parent.oid=child.iod_parent)
where child.oid is null;

or

select parent_name from parent
where not exists (select * from child where
  child.iod_parent=parent.oid);

Regards,
Tomasz Myrta