5.1 Introduction to View Objects

A view object is Oracle ADF component that encapsulates a SQL query and simplifies working with its results. By the end of this chapter, you'll understand all the concepts illustrated in Figure 5-1:

• You define a view object by providing a SQL query

• You use view object instances in the context of an application module that provides the database transaction for their queries

• You can link a view object to one or more others to create master/detail hierarchies

• At runtime, the view object executes your query and produces a row set of rows

• Each row is identified by a corresponding row key

• You iterate through the rows in a row set using a row set iterator

• You can filter the row set a view object produces by applying a set of query-by-example criteria rows

Figure 5-1 A View Object Defines a Query and Produces a RowSet of Rows

Note: To experiment with a working version of the examples in this chapter, download the DevGuideExamples workspace from the Example Downloads page at http://otn.oracle.com/documentation/jdev/b25947_01/ and see the QueryingDataWithViewObjects project.