Oracle Object Datatypes

An object type is a user-defined composite datatype created in the database. A column can represent an object type or a row can represent an object type. An instance of the Object type can be stored in the database. This object instance can be fetched to the client side and modified using Oracle Objects for OLE. There are two types of objects instance.

· If a column represents an object type, then an instance of this object type is referred as an embedded instance or a value instance. For example, an ADDRESS object type is stored as a column in the PERSON table. They can be embedded within other structures. An embedded instance or a value instance can also be the attributes of another object instance. In OO4O, object instance of this type are represented by an OraObject object.

· If a row in an object table represents an object type, then the instance of this type is referred to as a referenceable object. An internally referenceable object has an unique object identifier. This unique object identifier is represented by the REF data type. A REF column can be thought of as a pointer to a referenceable object. OO4O applications can retrieve a REF to a referenceable object, fetch (pin) the associated referenceable object to the client side, and update (flush) the modified referenceable object to the database. In OO4O, an object instance of this type represented by an OraRef object.

The following topics provide more information:

· Using the OraObject Interface

· Retrieving an Embedded/Value Instance from the Database

· Accessing Attributes of an Embedded/Value Instance

· Modifying Attributes of an Embedded/Value Instance

· Using the OraRef Interface

· Retrieving a REF from the Database

· Accessing Attributes of a Referenceable Instance

· Modifying Attributes of a Referenceable Instance