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From: Tomasz Myrta <jasiek@klaster.net>
To: Rajesh Kumar Mallah <mallah@trade-india.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: sql question regarding count(*)
Date: Thu, 06 Mar 2003 13:00:52 +0100
Message-ID: <3E673874.5030606@klaster.net> (raw)
References: <200303061702.26339.mallah@trade-india.com>

Rajesh Kumar Mallah wrote:
> When does count(*) returns "o rows" ?
> and when does it return 1 row value being 0.
> 
> tradein_clients=# SELECT count(*)   from public.eyp_listing  where sno> 0 and 
> amount> 0  group by sno,branch,edition having count(distinct userid) > 1 ;
>  count
> -------
> (0 rows)
> 
> tradein_clients=#
> tradein_clients=#
> tradein_clients=# SELECT count(*) from public.users where userid=-1;
>  count
> -------
>      0
> (1 row)
> 
> tradein_clients=#
It's because of your having clause.
If count(*)=0 then having count(*)>1 results in no rows.

Regards,
Tomasz Myrta

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