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ABAP CDS - Data Definitions
A CDS entity is a structured ABAP CDS object managed by ABAP Dictionary. When a CDS data definition is activated, it is created as metadata in CDS source code. CDS entities are not transported and are created after the transport of a piece of CDS source code when this code is activated in the target system. Each CDS entity is defined in a separate piece of CDS source code in the ABAP Development Tools (ADT). In the development tools, CDS entities are only visible as CDS definitions in their CDS source code. The ABAP Dictionary tool in ABAP Workbench (SE11) does not support any CDS data definitions of CDS entities. The ABAP runtime environment and other frameworks do not access the internal metadata of CDS entities. For example, the ABAP runtime environment does not recognize a CDS entity as a data type of ABAP Dictionary or as a potential data source of Open SQL statements. The name of a CDS must be unique accordingly.
As a data type in ABAP Dictionary, a CDS entity represents a structured type. In ABAP CDS, the CDS entity can be used as a data source in other CDS entities. In ABAP, a CDS entity can be specified after the TYPE addition to reference this structure type and its components in ABAP programs. The components of the structured type are, as usual, specified using the structure component selector cds_entity-comp. In Open SQL read statements, however, CDS entities cannot be accessed in Native SQL.
A CDS entity cannot be used as a data type in ABAP Dictionary. It cannot, for example, be used as a type of a substructure, as an include structure, or as the row type of a table type.
The following sections describe the possible CDS entities and the associated DDL statements:
A further section describes the problems that can arise due to cyclical dependencies between CDS entities.