Ok, I get it. Good education!
Thank you very much, saved me a big headache!
Edson
Em 03/02/2013 03:06, Pavel Stehule escreveu:
Hello
2013/2/3 Edson Richter <edsonrich...@hotmail.com>:
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?
sure
http://stackoverflow.com/questions/2246772/whats-the-difference-between-not-exists-vs-not-in-vs-left-join-where-is-null
Regards
Pavel
Thanks,
Edson
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