Question

Here’s a sample database table :

| ID | ProductID | DateChanged | Price
| 1  | 12        | 2011-11-11  |  93
| 2  | 2         | 2011-11-12  |  12
| 3  | 3         | 2011-11-13  |  25
| 4  | 4         | 2011-11-14  |  17
| 5  | 12        | 2011-11-15  |  97

Basically, what I want to happen is get the latest price of grouped by ProductID.

The result should be like this :

| ID | ProductID | Price 
| 2  | 2         |  12
| 3  | 3         |  25
| 4  | 4         |  17
| 5  | 12        |  97

If you notice, the first row is not there because there is a new price for ProductID 12 which is the row of ID 5.

Basically, it should be something like get ID,ProductID and Price grouped by productID where DateChanged is the latest.

Answer 1

select a.id, a.productid, a.price
from mytable a,
    (select productid, max(datechanged) as maxdatechanged
    from mytable
    group by productid) as b
where a.productid = b.productid and a.datechanged = b.maxdatechanged