Identity Column provide database application developers
with an easy way of automatically generating a numeric column value for
every row in a table. You can have this value generated as a unique value,
then define the identity column as the primary key for the table. To
create an identity column, include the IDENTITY clause in the CREATE TABLE
or ALTER TABLE statement. Identity column is supported in various
databases, such as, DB2, Oracle, SQL server and others.
Websphere application server does not support Identity Column as a
field in EJB. If you are using Identity Column to determine the primary
keys, the identity column has to be in a separate table (not in the EJB).
The identity value needs to be queried from the table, then used as the
EJB primaryKey.
|