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Re: avg() from multiple columns

From: Jason Tan <jason(at)rebel(dot)rebel(dot)net(dot)au>
To: Miia Uski <miia(dot)uski(dot)155(at)student(dot)lu(dot)se>
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re: avg() from multiple columns
Date: 2001-09-05 03:02:31
Message-ID: Pine.LNX.3.95.1010905122609.26091L-100000@rebel.rebel.net.au (view raw or flat)
Thread:
Lists: pgsql-novice

If you want row by row averages try this:

select (col1+col2+col3)/3 from table;

If you wnat to average several columns over the whole table this seems to
work:

select avg(col1+col2+col3) from table;

Regards
Jason

On Sun, 2 Sep 2001, Miia Uski wrote:

> I have a question regarding taking the average value from several
> columns.
> 
> I am trying to evaluate a survey with sql. I have one column per
> question, and one row per answered survey. The answers can have values 1
> 
> - 4, unanswered questions have 0. I want to take the average from the
> answers of several questions that belong to the same category. For one
> question I can do like this:
> 
> igv=> select avg("1.2") from igvdata
> igv-> where "1.2" > 0;
> 
> How do I go about to have averages for several columns? Do I have to
> create views in order to avoid the "no answer"-values for each column?
> 
> 
> Thanks in advance,
> 
> Miia
> 
> 
> 
> 
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--
------------------------------------------------------------------------------
Jason Tan                                                jason(at)rebel(dot)net(dot)au
     "Democracy is two wolves and a lamb voting on what to have for lunch. 
                 Liberty is a well-armed lamb contesting the vote."
                               ~Benjamin Franklin, 1759
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