[aelander]

Får ju problem redan här:

select * from TabellB;
+----+-----+------+------------+
| Id | PId | Pris | Datum      |
+----+-----+------+------------+
|  1 |   1 |  500 | 2011-12-21 |
|  2 |   2 |  600 | 2011-12-21 |
|  3 |   3 | 1000 | 2011-12-07 |
|  4 |   3 | 1800 | 2011-12-13 |
|  5 |   3 | 1500 | 2011-12-18 |
|  6 |   4 |  320 | 2011-12-01 |
+----+-----+------+------------+

mysql> select * from TabellB group by PId;
+----+-----+------+------------+
| Id | PId | Pris | Datum      |
+----+-----+------+------------+
|  1 |   1 |  500 | 2011-12-21 |
|  2 |   2 |  600 | 2011-12-21 |
|  3 |   3 | 1000 | 2011-12-07 |
|  6 |   4 |  320 | 2011-12-01 |
+----+-----+------+------------+

Vill att den ska välja det senaste priset för en PId