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Date: Wed, 30 Apr 2008 16:12:12 -0700 (PDT)
From: chester c young <chestercyoung@yahoo.com>
Subject: Re: columns for count histograms of values
To: Alexy Khrabrov <deliverable@gmail.com>
Cc: sql pgsql <pgsql-sql@postgresql.org>
In-Reply-To: <824FF9F9-9997-4AD9-9955-3CA658E150D4@gmail.com>
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--- Alexy Khrabrov <deliverable@gmail.com> wrote:

> Greetings -- I have a table of the kind
> 
> Ratings:
> id integer
> rating smallint
> 
> -- where value can take any value in the range 1 to 5.  Now I want to
>  
> have a statistical table Stats of the form
> 
> id integer
> min smallint
> max smallint
> avg real
> r1 integer
> r2 integer
> r3 integer
> r4 integer
> r5 integer
> 
> -- how can I create it in one pass over Ratings? 

select id, min(rating), max(rating), avg(rating),
  sum( case rating = 1 then 1 else 0 end ),
  ...


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