Search Postgresql Archives

Diferences between IN and EXISTS?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi!

Assumptions: PostgreSQL 9.2.2, Win64, already run vacumm full freeze analyze. No problems in the database. I know there are 1247 records to be found.
Why does these queries return different results:


select count(*) from parcela
where id not in (select parcela_id from cadastroservicoparcela);

count
--------
0


select count(*) from parcela
where not exists (select 1 from cadastroservicoparcela where parcela_id = parcela.id);

count
--------
1247


I can't figure out, I did expect that the first one returns exactly same result! Could null values in cadastroservicoparcela.parcela_id affect the first query?


Thanks,

Edson



--
Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux