From: Nagy László Zsolt <gandalf@shopzeus.com>
To: pgsql-admin@postgresql.org
Subject: sum, min, max and null
Date: Mon, 18 Aug 2014 20:21:37 +0200
Message-ID: <53F24431.9030801@shopzeus.com> (raw)
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-admin>
Hi,
I understand that sum, min and max ignore null values. So for example
this query:
select sum(v),min(v) from (
select 1 as v
union all select null
union all select 3
) s
will result in sum(v)=4 , min(v)=1.
However, I'm in need of a different interpretation, where sum() should
change the output value to null if there is any NULL value in the input.
How do I achieve this? I was experimenting with this:
select case when sum(hasnull)>0 then null else sum(v) end as mysum from (
select v, case when v is null then 1 else 0 end as hasnull
from (
select 1 as v
union all select null
union all select 3
) s ) s2
It works but this is so ugly that I'm not even trying to use it in
production code. Is there any better way to do it?
Thanks,
Laszlo
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To: pgsql-admin@postgresql.org
Cc: gandalf@shopzeus.com
Subject: Re: sum, min, max and null
In-Reply-To: <53F24431.9030801@shopzeus.com>
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