How to return multiple rows with the max value

Question

I'm currently doing a document management system that I'm having a few problems with. I want to be able to select and show each unique document with the highest version number This is my current code:

SELECT DISTINCT( policyheader.policytitle ), 
               Max(policyrecords.policyversion)    AS maxPolicy, 
               policyrecords.useruploaddate, 
               policyrecords.policydesc, 
               LEFT(policyrecords.whatchanged, 30) AS changes, 
               policyheader.policyref 
FROM   policyrecords 
       INNER JOIN policyheader 
               ON policyrecords.policyref = policyheader.policyref 
GROUP  BY policyrecords.policydesc, 
          policyrecords.policyversion 

I have also been trying IN as well. It is returning this data:

What I want it to return is this data:

Answer 1

You can approach this in several ways. The not exists method often performs well:

SELECT ph.policyTitle, pr.*
FROM policyrecords pr INNER JOIN
     policyheader ph
     ON pr.policyRef = ph.policyRef
WHERE not exists (select 1
                  from policyrecords pr2
                  where pr2.policyRef = pr.policyRef and
                        pr2.policyVersion > pr.policyVersion
                 );

This implements the following logic: "Get me all the records from policyrecords where there is no records with the same policyRef and a larger policyVersion ." This is a fancy way of saying get me the maximum version.

Answer 2

Try this query

SELECT
    DISTINCT(policyheader.policyTitle),
    MAX(policyrecords.policyVersion) AS maxPolicy,
    policyrecords.userUploadDate,
    policyrecords.policyDesc,
    left(policyrecords.whatChanged,30) as changes,
    policyheader.policyRef
FROM policyrecords
    INNER JOIN policyheader ON policyrecords.policyRef = policyheader.policyRef
GROUP BY
    DISTINCT(policyheader.policyTitle)

If you group by version, you will see all the versions for one policyTitle :)

Answer 3

SELECT
 policyheader.policyTitle,
 policyrecords.policyVersion,
 policyrecords.userUploadDate,
 policyrecords.policyDesc,
 left(policyrecords.whatChanged,30) as changes,
 policyheader.policyRef
 FROM policyrecords
 INNER JOIN policyheader ON policyrecords.policyRef = policyheader.policyRef
 GROUP BY
 policyrecords.policy
 order by policyrecords.policyVersion desc