Richard Huxton said:
> 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.
>> 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?
Yes, there is a null value and it has not to be there.
Thank you.
Bye, \ferz
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