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. See also Join, Projection and Selection.

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 use the join condition from a foreign key defined between the tables (see Foreign Key Relationship and Join Condition). In the third step, you must select the fields of the base tables to be used in the view. Selection conditions that restrict the records in the view can be formulated in the fourth step.

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

• Database views are implemented with an equivalent view on the database.

• Projection views are used to hide fields of a table (only projection).

• Help views can be used as selection method in search helps.

• Maintenance views permit you to maintain the data distributed on several tables for one application object at one time.

Database views implement an inner join. The other view types implement an outer join (see Inner and Outer Join).

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 in a maintenance view or help view if they are linked to one another with foreign keys.

The maintenance status defines whether you can only read data with the view or whether you can also insert and change data with it.

Example for Views

Creating Views

Deleting Views