Re: aggregate functions, COUNT - Mailing list pgsql-sql

From Stephan Szabo
Subject Re: aggregate functions, COUNT
Date
Msg-id Pine.BSF.4.21.0110020944100.46517-100000@megazone23.bigpanda.com
Whole thread Raw
In response to aggregate functions, COUNT  (Kevin Way <kevin.way@overtone.org>)
Responses Re: aggregate functions, COUNT  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-sql
On Tue, 2 Oct 2001, Kevin Way wrote:

> I'm currently using a SELECT count(*) when all I really want to know is
> if 1 or more records exist.  Is there a standard way to just find out if
> a record exists?  If not, is there a way to avoid iterating over all the
> records by writing an aggregate function?  Given what I've read of how
> they work, I don't see how to make the function return before parsing
> all the results anyway, am I wrong here?

I think you could use EXISTS for that,
select EXISTS (<query>); should give a true/false on whether the 
query returned any rows.  I'm not sure if it stops after one row
or not, but if it doesn't you can add a limit 1 to the query.





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