Hi,
I have a table that has columns A,B and C. “A” and “B” composes primary key together. And hbm.xml looks like ;
<class name="Table1" table="TABLE1">
<composite-id >
<key-property name="a" type="int">
<column name="A" />
</key-property>
<key-property name="b" type="int">
<column name="B" />
</key-property>
</composite-id>
<property name="c" column="C" not-null="true" />
</class>

And my problem is column “A” should be auto generated and column “B” should be assigned. For example table looks like this with data;

A B C
1 1 Ex1
2 1 Ex2
3 2 Ex3

And when inserting new value into table how can i auto increment column “A” and assign a custom value to column “B” using hibernate? Can i do that with defining column “A” as identity in database and how should this be specified in hibernate?

This is a pretty tricky question. I will watch this thread if some one responds back.
I don't think it is possible to do what you are looking for lets see if someone else has a solution for this.
The reason I don't think its possible is because database generated value will only be created when Hibernate issues an insert until the value is inserted, the generated value is not available to hibernate. So you might have to do is get the generated value for column "A" read the value by loading the object, then issue an update on the column "B" if the Column "A" and Column "B" values are unique per composite-id requirement, then the update will be successful other wise it will fail.

Question - what is the business requirement for this.

From the Hibernate documentation at http://docs.jboss.org/hibernate/stable/ ... ompositeid



But if column A is auto-generated it usually means that it is unique by itself. Why not use only A as the id?

Actually this table is about exchange and contains exchange offers. Offers can be divided into multiple parts. And then each part becomes an offer which are representing by orginal offer id. In this example column “A” describes offer id and “B” the partition of offer. For example after first offer insert the value for offer and partition id should be like A = 1, B=0. After division there will be 2 data for offer whose id = 1 and table should look like this;
A B
1 0
1 1
And with each division i will assign a value for “B” and give the original id to “A”. But when a new offer comes i want to increase the offer id “A”.
A B
1 0
1 1
2 0

However i realized you are right if i specify column “A” auto generated i wont able to assing value when a division occurs. So i decided define “A” and “B” assigned and i generate id for “A” from a sequence table which i’ll create.
Thanks a lot.