Question

Possible Duplicate:
MySQL retrieve latest record for Group

I have a query that groups all records that have the same information in the ‘address1’ field, unless they have a different jobType.

SELECT * 
FROM   jobs 
WHERE  client_id = '".$id."' 
       AND status = '3' 
GROUP  BY CASE 
            WHEN jobType IN ( '0', '3', '6' ) THEN '0' 
            ELSE jobType 
          end, 
          address1 
ORDER  BY Max(id) ASC 

The problem I’m running into, is that the query always pulls the first instance in the group. I need it to pull the latest instance in the group. I’ve tried a few variations of ORDER BY, and that hasn’t seemed to do the trick.

Any help would be greatly appreciated.

Answer 1

You want the groupwise maximum:

SELECT jobs.*
FROM   jobs NATURAL JOIN (
  SELECT   MAX(id) id
  FROM     jobs
  WHERE    client_id = :id AND status = '3'
  GROUP BY CASE
             WHEN jobType IN ('0','3','6') THEN '0'
             ELSE jobType
           END,
           address1
) t

However, this won’t be very index-friendly. Better to create a column that contains the result of your CASE expression (and then index that).