id tmpname date_used tkt_nr
---|---------|------------------|--------|
1 | template| 04/03/2009 16:10 | 00011 |
2 | templat1| 04/03/2009 16:11 | 00011 |
5 | templat2| 04/03/2009 16:12 | 00011 |
3 | diffname| 03/03/2009 15:11 | 00022 |
4 | diffname| 03/03/2009 16:12 | 00022 |
6 | another | 03/03/2009 16:13 | NULL |
7 | somethin| 24/12/2008 11:12 | 00023 |
8 | name | 01/01/2009 12:12 | 00026 |
I would like to have the result:
id tmpname date_used tkt_nr
---|---------|------------------|--------|
5 | templat2| 04/03/2009 16:12 | 00011 |
4 | diffname| 03/03/2009 16:12 | 00022 |
7 | somethin| 24/12/2008 11:12 | 00023 |
8 | name | 01/01/2009 12:12 | 00026 |
So what I’m looking for is to have distinct tkt_nr values excluding NULL, based on the max value of datetime.
I have tried several options but always failed
SELECT *
FROM templateFeedback a
JOIN (
SELECT ticket_number, MAX(date_used) date_used
FROM templateFeedback
GROUP BY ticket_number
) b
ON a.ticket_number = b.ticket_number AND a.date_used = b.date_used
I would appreciate any help. Unfortunately I need the code to be compatible with SQL Server.
I’ve stopped doing things this way since I discovered windowing functions. Too often, there are two records with the same timestamp and I get two records in the resultset. Here’s the code for tSQL. Similar for Oracle. I don’t think mySQL supports this yet.