Re: Do I just not understand count()

Try

select sum(case when a=1 then 1 else 0 end), sum(case when a=2 the 1 else 0
end) from t;

to get the number of occurrences of each value.

Jim Ballard

----- Original Message -----
From: "Clinton Adams" <clinton@vote-smart.org>
To: "Ben" <bench@silentmedia.com>
Cc: <pgsql-general@postgresql.org>
Sent: Monday, April 08, 2002 12:49 PM
Subject: Re: [GENERAL] Do I just not understand count()


> > If I have the table t defined as:
> >
> >  a
> > ---
> >  1
> >  1
> >  2
> >
> >
> > and I say:
> >
> > select count(a=1) from t;
> >
> > should it give me 1 or 2 as a result? I'm getting 2, and I'd think I
> > should get 1....
> It will give you a result of 3, as a=1 does not toss out rows for which a
<>
> 1.
>
> You would need to add some parameters to limit the rows that count is
> countin...
> select count(a) from t where a = 1
> would give you 2
>
> select count(DISTINCT a) from t where a = 1
> would give you 1
>
>
>
>
> >
> >
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