Hi, I'm storing data against a bunch of people and want to track how it changes. So, I have a person table where everyone has a person ID and a results table a bit like this:
| personID | classification | date | | 1 | 0 | 2005-11-10 | | 2 | 3 | 2005-11-10 | | 3 | 1 | 2005-11-10 | | 4 | 0 | 2005-11-10 | | 1 | 3 | 2005-12-01 | | 4 | 2 | 2005-12-03 | | 1 | 2 | 2005-12-23 | | 5 | 1 | 2006-01-03 | | 2 | 2 | 2006-12-03 | This lets me see how things change as a pattern, for example comparing a a SELECT classification WHERE DATE < '2006-01-01' GROUP BY classification and comparing it to: SELECT classification WHERE DATE >= '2006-01-01' AND DATE <= '2006-01-31' GROUP BY classification But is there a way I can select every personID's most recently expressed preference? I hope this makes sense - in the table above, person 1 had a classification of 0 at 10th November, but this changed to 2 on 23rd Decembner. Can I write a query to select personID once together with their latest preference, or indeed their preference as expressed at a specific point in time? Thanks as ever for any suggestions. Russell. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
