Russell - This should basically work for selecting the most recently selected preference...
SELECT DISTINCT personID, classification FROM results_table ORDER BY date DESC On 4/10/06, Russell Horn <[EMAIL PROTECTED]> wrote: > > 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] > >
