Introduction

View objects are an essential part of the ADF business components. They work in conjunction with entity objects, making entity-based view objects , to support querying the database, retrieving data from the database, and building rowsets of data. The underlying entities enable an updatable data model that supports the addition, deletion, and modification of data. They also support the enforcement of business rules and the permanent storage of the data to the database.

In cases where an updatable data model is not required, the framework supports a read-only view object , one that is not based on entity objects but on a SQL query supplied by the developer. Read-only view objects should be used in cases where UNION and GROUP BY clauses appear in the view object queries. In other cases, even though an updatable data model is not required, the recommended practice is to base the view objects on entity objects and allow the JDeveloper framework-supporting wizards to build the SQL query automatically instead.

This chapter presents several techniques covering a wide area of expertise related to view objects.