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Re: Creating a selective aggregate ??

From: "Greg Sabino Mullane" <greg(at)turnstep(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Cc: nabifadel(at)usj(dot)edu(dot)lb
Subject: Re: Creating a selective aggregate ??
Date: 2004-07-03 16:36:36
Message-ID: e163eaf2877e3a6b214f2016f5bd8a3c@biglumber.com (view raw or flat)
Thread:
Lists: pgsql-hackers
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Hash: SHA1
 
> I am searching for a way to have the minimum date and maximum
> date for dates seperated by one week whitout gaps between them.
 
This is not something you can accomplish (easily) with just SQL,
so you will need some sort of higher language. Here's a little
function I came up with, which might do what you want:
 
CREATE OR REPLACE FUNCTION noweekgaps() RETURNS SETOF TEXT AS '
DECLARE
  startday TEXT;
  endday TEXT;
  lastone INT;
  mydiff INT;
  myrec RECORD;
BEGIN
  
FOR myrec IN SELECT TO_CHAR(d, \'Mon DD, YYYY\') AS z,
    TO_CHAR(d,\'J\')::integer AS j FROM t ORDER BY d ASC LOOP
  IF startday IS NULL THEN
    startday := myrec.z;
  ELSE
    mydiff := myrec.j - lastone;
    IF mydiff > 7 THEN
      RETURN NEXT startday || \' - \' || endday;
      startday := myrec.z;
    END IF;
  END IF;
  lastone := myrec.j;
  endday := myrec.z;
END LOOP;
  
IF endday IS NOT NULL THEN
  RETURN NEXT startday || \' - \' || endday;
END IF;
  
RETURN;
END;
' LANGUAGE plpgsql;
 
 
 
- --
Greg Sabino Mullane greg(at)turnstep(dot)com
PGP Key: 0x14964AC8 200407031237
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