Oracle JHeadstart Developer's Guide - Downloads - Oracle

3.2.4. Generating Primary Key Values
Now, if you need to code logic in the Employee Entity Object that requires access to the
departments an employee manages, you can call the getDepartmentsManaged()
method rather than the confusing getEmployees() method.
In many cases, artificial primary keys are used (also known as surrogate primary key).
Typically, these primary key columns are called ID. Because they are artificial, they are
meaningless to the user. The system generates the values and uses them internally, but
they should be hidden for the user.
Before starting to generate applications with JHeadstart, examine your Model for
artificial primary keys. Make sure they are correctly populated. Test this with the
Business Components Application Module Tester. See section Test the model.
An artificial primary key can be populated in two ways:
• In the Business components: The create method of the entity object is used for
that.
• In the database: A database trigger is in added to the table that gets the next
value from a database sequence and populates the primary key.
3.2.4.1. Surrogate primary key populated in the Business Components Model layer
In the Entity object implementation, a create method is added that takes the value out of
a database sequence and sets the primary key.
This is described in detail in the JDeveloper Help. Check topic ‘Populating an Attribute
from a Database Sequence’.
JHeadstart Developer's Guide Creating ADF Business Components 3 - 7