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