Thread: SQL query question

SQL query question

From

"Joost Kraaijeveld"

Date:

22 December 2004, 15:50:30

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?

TIA

Groeten,

Joost Kraaijeveld
Askesis B.V.
Molukkenstraat 14
6524NB Nijmegen
tel: 024-3888063 / 06-51855277
fax: 024-3608416
e-mail: J.Kraaijeveld@Askesis.nl
web: www.askesis.nl

Re: SQL query question

From

Tomasz Myrta

Date:

22 December 2004, 16:37:17

> 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