hi there,

I've got the following legacy database structure (3 tables):
USER, with seq_nr as pk (pk contains 1 column)
ORDER, with seq_nr, user as pk (pk contains 2 columns)
ORDER_ITEM, with seq_nr, order as pk (pk contains 3 columns)

I've mapped the ORDER table fine:
<class name="Order, DB" table="ORDR_ORDER">
<composite-id name="Pk" class="OrderPk, DB">
<key-property name="SequenceNumber" column="SEQ_NR" />
<key-many-to-one name="User"
class="User, DB"
column="FK_USER_SEQ_NR"/>
</composite-id>
</class>

I'm having trouble mapping the ORDER_ITEM table, however. The structure would look similar to the above. I'd specify a key-property (with name SequenceNumber), but I'd like to specify multiple columns in the <key-many-to-one> tag -- that the property is "Order" and the columns are FK_ORDR_SEQ_NR and FK_ORDR_USER_SEQ_NR.

Can I have a composite-id containing a foreign key to a table with more than 1 column in its primary key?

thanks,
Manoj

Your composite_id is missing <key-property name="user" column="USER"/> for ORDER table, and for ORDER_ITEM mapping instead of column="FK_USER_SEQ_NR" attribute use <key> element, something like:
<key>
<column name="FK_USER_SEQ_NR"/>
<column name="FK_ORDR_SEQ_NR "/>
</key>

hey there,

I can use <key>, but that'll be to identify a relationship between order-item and order - not to define a composite identifier on order-item. NHibernate (Hibernate 2.1) doesn't let me have a <key> tag within a <composite-id> tag.

A possible solution (but impractical here - I'm working with an existing schema) would be to create a surrogate key (sequence number?) for order-item, and create a (composite) foreign key to order.

But - how do I specify an identifying composite-foreign-key relationship?

thanks,
Manoj

hi there,

I've got a suitable solution -- found this out by using MiddleGen to generate mapping files (great tool!)

I've got my composite-id tag defined as follows:

Further down I define my composite foreign key (using the update="false" and insert="false" tags) referencing the same columns:


This allows me to define a complex primary-key, and still use parts of the primary key in relationships.

thanks,
Manoj