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ABAP CDS - Projection Views

A CDS projection view is defined in the DDL source code of a CDS data definition using the statement DEFINE [TRANSIENT] VIEW ENTITY AS PROJECTION ON in the CDS DDL of the ABAP Core Data Services (CDS). DDL source code in a CDS projection view can also be displayed in Repository Browser in ABAP Workbench.

A CDS projection view is based on another CDS view entity (called projected entity). CDS projection views adapt a CDS data model for service-specific use cases.

The name of a CDS projection view is in the namespace of all global types of an AS ABAP.

Client handling is done implicitly and automatically for CDS projection views. The rules are the same as for CDS view entities, see section ABAP CDS - Client Handling in CDS View Entities.

Table buffering does not work for CDS projection views, since buffering in general does not work with another CDS view as data source.

There are different types of projection views available, depending on the purpose and use case of the projection view. The type of projection view is specified using the syntax addition PROVIDER CONTRACT. The following types of CDS projection views are available:

• CDS transactional queries

  Transactional queries define the projection layer of a RAP business object. They are CDS SQL entities.

  For details, see the section about Transactional Queries.

• CDS transactional interfaces

  CDS transactional interfaces serve as stable public interface layer in a CDS data model. They are typically used in the context of the ABAP RESTful Application Programming Model to provide the basis for a RAP BO interface.

  CDS transactional interfaces are SQL entities.

  For details, see the section about CDS Transactional Interfaces.

• CDS analytical queries

  CDS analytical queries are intended for modelling analytical queries within the CDS data model. They are evaluated by an analytical engine.

  Analytical queries are non-SQL entities.

  For details, see the section about Analytical Queries.

• no provider contract specified

  Deprecated. It is strongly recommended that a provider contract is specified. If no provider contract is specified, the same features are available as for transactional queries. There are only a few differences in the syntax checks to transactional queries. The differences are listed in topic no contract.

Further Information

ABAP Data Models development guide, section about CDS projection views.

Hint

A CDS projection view can be extended using a CDS view entity extension EXTEND VIEW ENTITY. For details, see topic CDS DDL - EXTEND VIEW ENTITY.

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CDS DDL - CDS Projection View, Transactional Queries
CDS DDL - CDS Projection View, Transactional Interface
CDS DDL - CDS Projection View, Analytical Queries
CDS DDL - CDS Projection View, No Contract