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ABAP CDS - Data Definitions

CDS data definitions are made using the ABAP CDS DDL in CDS source code. CDS data definitions can be used to defined (and possibly enhance) CDS entities:

• CDS views

• CDS table functions

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:

• CDS views

• CDS table functions

• DDL statements

A further section describes the problems that can arise due to cyclical dependencies between CDS entities.

Notes

• The CDS source code of a data definition for a CDS entity does not need to have the same name as the entity, but this is recommended.

• In activations, the names of a piece of CDS source code, the CDS entity, and (if necessary) the CDS database view construct an indivisible defining unit. After a piece of CDS source code is transported for the first time, this defining unit cannot be used elsewhere and none of the names used can be modified. More specifically, the following applies:

• In a piece of CDS source code, the name of a CDS entity or a CDS database view cannot be renamed.

• A CDS entity or CDS database view cannot be used in a different piece of CDS source code, if the original source code was deleted.

• A piece of CDS source code already used for a CDS entity or CDS database view cannot be used for a different CDS entity or CDS database view.

The same applies to the CDS source code of a CDS view extension and its append view.

• The CDS source code in data definition for a CDS entity is edited in a different editor from the CDS source code of a CDS role for CDS access control. The ADT documentation describes how the different types of source code are created.

• The program DEMO_SHOW_DDL_SOURCE displays CDS source code in SAP GUI.

• A structure type defined using a CDS entity exists alongside the classic structures in ABAP Dictionary.

Continue
ABAP CDS - Views
ABAP CDS - Table Functions
ABAP CDS - DDL Statements
ABAP CDS - Cyclical Dependencies