Introduction to Object Datatypes

Introduction to Object Datatypes

Relational database management systems (RDBMSs) are the standard tool for managing business data. They provide reliable access to huge amounts of data for millions of businesses around the world every day.

Oracle is an object-relational database management system (ORDBMS), which means that users can define additional kinds of data—specifying both the structure of the data and the ways of operating on it—and use these types within the relational model. This approach adds value to the data stored in a database. Object datatypes make it easier for application developers to work with complex data such as images, audio, and video. Object types store structured business data in its natural form and allow applications to retrieve it that way. For that reason, they work efficiently with applications developed using object-oriented programming techniques.

Complex Data Models

The Oracle server lets you define complex business models in SQL and make them part of your database schema. Applications that manage and share your data need only contain the application logic, not the data logic.

Complex Data Model Example

For example, your firm might use purchase orders to organize its purchasing, accounts payable, shipping, and accounts receivable functions.

A purchase order contains an associated supplier or customer and an indefinite number of line items. In addition, applications often need dynamically computed status information about purchase orders. For example, you may need the current value of the shipped or unshipped line items.

Later sections of this chapter show how you can define a schema object, called an object type, that serves as a template for all purchase order data in your applications. An object type specifies the elements, called attributes, that make up a structured data unit, such as a purchase order. Some attributes, such as the list of line items, can be other structured data units. The object type also specifies the operations, called methods, you can perform on the data unit, such as determining the total value of a purchase order.

You can create purchase orders that match the template and store them in table columns, just as you would numbers or dates.

13-2 Oracle9i Database Concepts