On Wed, Mar 23, 2011 at 4:08 PM, <tv@xxxxxxxx> wrote:
This looks like to give expected results. Also note that the where clause "is null" is really required and is not an
optional predicate.
> I just want to retrieve that id 's from page_content which do not haveIn that case the query probably does not work (at least the query you've
> any entry in clause2 table.
sent in the first post) as it will return even those IDs that have at
least one other row in 'clause2' (not matching the != condition). At least
that's how I understand it.
true.
So instead of this
from page_content p, clause2 c where p.crawled_page_id != c.source_id ;
select distinct(p.crawled_page_id)
you should probably do this
from page_content p left join clause2 c on (p.crawled_page_id =
select distinct(p.crawled_page_id)
c.source_id) where (c.source_id is null);
I guess this will be much more efficient too.
This looks like to give expected results. Also note that the where clause "is null" is really required and is not an
optional predicate.
regards
Tomas
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Regards,
Chetan Suttraway
EnterpriseDB, The Enterprise PostgreSQL company.
