Re: Weird NOT IN condition in SELECT (PostgreSQL 7.4.3

Ferruccio Zamuner wrote:
> Hi,
>
> I've following select, and I expect to receive a single record as result
> from it:
>
> select c.id
> from copie as c
> where c.enum=46857 and
> c.condizio_prestito = 'A' and
> c.id not in (select id_copia from testi_fermi_prenotati) and
> c.id not in (select id_copia from prestiti);
>
> but it doesn't give me any records at all.
>
>
> Following there is table descriptions:
>
> CREATE TABLE copie (
> id serial NOT NULL primary key,

> CREATE TABLE prestiti (
> id_copia integer references copie(id)

> CREATE TABLE testi_fermi_prenotati (
> id_copia integer NOT NULL references copie(id),

Are you sure you don't have any null values in prestiti.id_copia?

--
Richard Huxton
Archonet Ltd