Giovanni schrieb:
> select prova,risoluzione, inizio, timediff(risoluzione,inizio) as
> delta
> from statistiche where (prova=1 and risoluzione is not null) order by
> diff asc
>
> but i get this result:
> risoluzione inizio diff
> 2007-04-29 15:16:55 2007-04-29 15:15:55 00:01:00
> 2007-05-02 23:25:04 2007-05-02 23:23:57 00:01:07
> 2007-05-05 20:28:21 2007-05-05 20:26:12 00:02:09
> 2007-05-05 10:21:08 2007-05-05 10:18:47 00:02:21
> 2007-04-30 16:52:50 2007-04-30 16:45:37 00:07:13
> 2007-05-05 14:23:42 2007-05-05 13:40:07 00:43:35
> 2007-04-29 23:58:17 2007-04-29 22:26:36 01:31:41
> 2007-05-05 16:35:21 2007-04-30 21:10:16 115:25:05 <------*
> 2007-05-04 12:07:43 2007-05-01 08:58:28 75:09:15
> 2007-05-04 23:43:53 2007-05-01 14:11:14 81:32:39
>
> Why the * row, is not ordered?

It seems to be in lexicographic order ('01:31:41' < '115:25:05' <
'75:09:15').

Let me guess:
You subtract two date/time values to get a diff.
Behind the scenes, the result is some duration type, which gets
converted to a string when storing in the 'diff' column.
Mysql then sorts strings since it doesn't know that the values are
really durations.

You may want to take a look at the Data Types chapter of mysql; I'm
pretty sure that it does have a data type for representing durations,
and these should then sort just as you intended.

HTH
Jo