zeusix.netcom.com
Date: Mon Jan 17 2005 - 17:45:22 CST

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Hi there:

I have a "How do I..." SQL question regarding selecting
distinct values from a field not included in an aggregated
query when LIMIT is in effect, illustrated by the
following example:

Table a contains the names of individuals, the places
they have visited and the year in which they were visited.

Let's see who has visited where and when:

SELECT * FROM a;

 name place year
------ ------- ------
 kim north 2004
 kim south 2003
 kim south 2003
 bob west 2004
 bob west 2004
 bob west 2003
 joe south 2004
 joe south 2005
 sue west 2004
 bob east 2003
 joe east 2004
 joe east 2004
 sue south 2004
 bob north 2004
 bob north 2005

Summarize data by number of places visited by year:

SELECT count(*) AS count, name, year FROM a
  GROUP BY name, year
  ORDER BY count DESC, name ASC;

 count name year
------- ------ ------
   3 bob 2004
   3 joe 2004
   2 bob 2003
   2 kim 2003
   2 sue 2004
   1 bob 2005
   1 kim 2004
   1 joe 2005

Return only four rows beginning at second row:

SELECT count(*) AS count, name, year FROM a
  GROUP BY name, year
  ORDER BY count DESC, name ASC
  LIMIT 4 OFFSET 1;

 count name year
------- ------ ------
   3 joe 2004 s,e,e
   2 bob 2003 w,e
   2 kim 2003 s,s
   2 sue 2004 s,w

Select only places visited included in LIMITed query:

SELECT DISTINCT place FROM a ????;

 place
-------
 south
 west
 east

Note that the place north does not appear in the last result
because north was only visited by bob in 2005 and kim in 2004,
records which are not included in the limited result.

Any help appreciated.

I would like to be compatible with 3.23.xx.

-Bob

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