I have two tables :
Session_instance and Centre , the columns are listed below :

TABLE session_instance

FORMAT_NAME ---- NOT NULL ---- VARCHAR2(20)
SESSION_ID ----NOT NULL ----VARCHAR2(5)
CENTRE_ID ---- NOT NULL ----VARCHAR2(5)
CUTOFF_PERIOD ---- NUMBER
RESERVED_PLACES_NUMBER----NUMBER

TABLE centre

CENTRE_ID ---- NOT NULL ---- VARCHAR2(5)
ONLINE_BOOKING_ENABLED ---- NOT NULL----CHAR(3)
WEBSITE----VARCHAR2(1000)

There are some more columns in both the tables

Now the mapping XML is like :

<hibernate-mapping package="org.ba.businesstier.bo">

<class name="CentreOnlineDetailBO" table="centre">
<id name="centreID"
column="centre_id" type="string">
</id>
<property name="onlineBooking" column="online_booking_enabled" type="string"/>
<property name="onlinePayment" column="payment_options" type="string"/>

<set name="centreSessionDetails" table="session_instance"
lazy="true"
inverse="true"
cascade="all, delete-orphan"
sort="unsorted">
<key>
<column name="centreID" not-null="true"/>
</key>
<one-to-many class="CentreSessionDetailsBO"/>
</set>


</class>
</hibernate-mapping>

-----------------------------------------------------------------------------------

<hibernate-mapping package="org.ba.businesstier.bo">
<class name="CentreSessionDetailsBO" table="session_instance">
<!-- <id name="testDate"
column="session_id" type="string">
</id> -->
<composite-id>
<key-property name="centreID" column="centre_id" type="string" />
<key-property name="testDate" column="test_date" type="date"/>
</composite-id>
<property name="cutOffPeriod" column="cutoff_period" type="string"/>
<property name="reservePlaces" column="reserved_places_number" type="string"/>
</class>
</hibernate-mapping>

All the Properties(gettters and setters) are covered in the BO.
I dont have the session ID , its not needed i just need to update all the sessions for a given centre in session_instance table ,thats why dont represent it in the XML

Now as u notice and as i had mentioned there are many other columns in both the tables but i dont need that data as such, so i have only those that are required in the XML and the BO's.

Now when i set all the values are try to update ( i dont have to insert in my requirement ) . I only do a update , so that both the tables are updated :

I get a error stating that

Caused by: java.sql.BatchUpdateException: ORA-01400: cannot insert NULL into ("C
A_ADMIN"."SESSION_INSTANCE"."FORMAT_NAME")

why is this happening ???? Any clues would be very helpful.. I am new to Hibernate so it could even be very very trivial :-)

This usually indicates you are trying to save a 'null' value in a NOT NULL column. Indeed that column is NOT NULL in the table definition. My theory is that since you have not included SESSION_INSTANCE.FORMAT_NAME in your mapping of the CentreSessionDetailsBO object, Hibernate does not know how to update that field. Instead Hibernate will try to set FORMAT_NAME to 'null', and the database won't allow that and thus the exception.

I would add the FORMAT_NAME to your CentreSessionDetailsBO mapping, make sure your updates do not set it to null, and see if the problem is gone.

Frank