BUG #2251: NOT IN clause is not working correctly
The following bug has been logged online:
Bug reference: 2251
Logged by: Sergei Dubov
Email address: sdubov@gmail.com
PostgreSQL version: 8.1.2
Operating system: Windows XP
Description: NOT IN clause is not working correctly
Details:
I have two tables, let's say A and B.
B is a child of a in one to many relationship. A contains records that are
not referenced by B.
I am running a query:
select * from A t1 where t1.id not in (select t2.A_id from B t2);
It returns 0 rows.
Now I run
(select t1.id from A t1) except (select t2.A_id from B t2);
And now Postgres correctly returns records from A that are not referenced by
B.
Thanks a lot for your consideration of this bug.
Serge.
On Fri, 10 Feb 2006, Sergei Dubov wrote:
I have two tables, let's say A and B.
B is a child of a in one to many relationship. A contains records that are
not referenced by B.I am running a query:
select * from A t1 where t1.id not in (select t2.A_id from B t2);
It returns 0 rows.
Now I run
(select t1.id from A t1) except (select t2.A_id from B t2);And now Postgres correctly returns records from A that are not referenced by
B.
This may not be a bug, since these two queries will do different things if
there are any nulls in B.A_id according to spec AFAIK. The short form is
that rvc NOT IN (<subselect returning nulls>) will not return true.