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