By defining views, logical views permitting access to certain data can be created specially for the application. The structure of such a view is defined by specifying the tables and fields used in the view.

A view can be used to combine the data distributed in several tables. Fields which are not required can be masked out, minimizing interfaces.

The data of a view is derived from one or more tables, but not stored physically. The simplest form of deriving data is to mask out one or more fields from a base table (projection) or to include only certain entries of a base table in the view (selection). More complicated views can comprise several base tables, the individual tables being linked with a relational join operation.

The base tables of the view must be selected in the first step of a view definition. In the second step, these tables must be linked by defining the join conditions. It is also possible to copy the join condition from foreign key defined between the tables. In the third step, you must select the fields of the base tables to be used in the view. Selection conditions which restrict the records in the view can be formulated in the fourth step.

Four different types of view are supported. These differ in the way in which the view is implemented and in the methods permitted for accessing the view data.

The join conditions for database views can be formulated using equality relationships between any base fields. The join conditions for the other view types must be obtained from existing foreign keys. Tables therefore can only be combined into a maintenance view or help view if they are linked to one another with foreign keys.