Hibernate version: 2

I have a mapped object, let's call it product:
------------------------------
| id | .... other colums |
--------------------------------
| 1 | ...
| 2 | ...
and a table representing monthly data related to this product.

------------------------------------
| product_id | month | data
-----------------------------------
| 1 | 20060201 | 50
| 1 | 20060101 | 60
| 1 | 20051201 | 40
etc.

I need to map the data object in such a way that when the
product is loaded, data for the current month and 11 previous months
is loaded with it).

Any ideas to do this in the most efficient way possible?
Thanks.
-Jeff

I would create a filtered collection with the condition you want as a SQL filter (see "where" attribute for collections), and map it with lazy="false" (and perhaps fetch="select" if necessary)

Ok, let's say I map this data object as a map:
<map
name="datamap"
table="datatable"
>
<key column="PRODUCT_ID">
</key>

<element
column="MONTH"
type="Date"
not-null="false"
unique="false"
/>
<element
column="DATA"
type="double"
not-null="false"
unique="false"
/>

</map>

And I use criteria api to retrieve my products. Where and how would
I put a filter?

You should put 'where="SQL where condition"' as attribute in <map> element.
As for the exact SQL where condition, I am no SQL expert, but it should not be too hard to put the condition you need - maybe define your own function in the database, depending on the database you have.