# Using a Domain as a Data Type for an Attribute

Because the database data types are in SQL and the business logic tier types are in Java, Business Components for Java needs to translate between the two.

For reverse generation:

- If you let a wizard generate default entity objects, it uses the predefined data type mappings. For Oracle Object Types and types that do not have predefined mappings, it attempts to create a domain for the type. You can change the data type after reverse generation, if needed.

- If you create an entity object by using the Entity Object Wizard, you can specify what data types and domains to map to your database columns before reverse generation. You can optionally create custom domains for certain column types.

For forward generation, you create an entity object for each entity by using the Entity Object Wizard and Editor, which includes specifying data types for each attribute. You need to create custom domains for attribute data types that are not available in the predefined business component data types. You use these entity objects to create your database tables with the Create Database Objects Tool.

#### To assign a domain as the data type of an attribute:

1. If an appropriate domain does not already exist, create a domain.

2. In the Entity Object Wizard or Editor, assign the domain as a data type for an attribute.

Related topics
Ways to Represent Oracle Object Types in Entity Objects
About Generating Entity Objects, Associations, and Database Tables
What Is an Entity Object?
What Is an Entity Attribute?
Business Component Data Types
Ways to Represent Oracle Object Types in Entity Objects