CDS Views in SAP ABAP with code

CDS Views in ABAP

Core Data Services (CDS) Views are an integral part of SAP’s next-generation data modeling infrastructure. These views are more advanced than traditional database views (DDIC views) and are designed to take full advantage of the in-memory capabilities of SAP HANA. They form the foundation of the modern ABAP programming model, particularly in SAP S/4HANA, which is built around a virtual data model (VDM) architecture.

What is a CDS View?

A CDS View is a reusable data model that defines the projection of data from one or more database entities. Unlike traditional database views, CDS views go beyond simple projections and joins by allowing advanced modeling capabilities directly at the database level.

CDS views are not persistent entities; they are virtual models that represent relationships within a database. This allows for real-time data access and minimizes the data load on the application server, thanks to the concept of code pushdown, which ensures data-intensive operations are handled directly by the HANA database.

Why Use CDS Views?

CDS views have numerous benefits:

- Code Pushdown: With CDS, operations are executed at the database level, reducing load on the application server.

- VDM: SAP S/4HANA uses CDS in the form of the Virtual Data Model, which allows for optimized data consumption.

- Reusable Data Models: CDS views are reusable and provide a clear separation between the data model and application logic.

- Enhanced Capabilities: CDS views go beyond DDIC views with advanced functions like associations, joins, and parameters.

Key Features of CDS Views:

- CDS views are part of the ABAP programming model.

- Defined and consumed at the database level, not the application level.

- Used in conjunction with SAP HANA to harness real-time, in-memory capabilities.

Basic Structure of CDS Views

The structure of a CDS view involves annotations that define its behavior, such as the name, description, and security checks. Here’s a breakdown:

1. @AbapCatalog.sqlViewName: Defines the corresponding SQL view name in the ABAP Dictionary (SE11).

2. @AbapCatalog.compiler.compareFilter: Enables comparison filters at the database level.

3. @AbapCatalog.preserveKey: Ensures that key fields are preserved in the generated view.

4. @EndUserText.label: Provides a description for the CDS view.

5. @AccessControl.authorizationCheck: Defines the level of authorization check required for the CDS view.

Example: Simple CDS View

Let’s look at a simple CDS view that selects material data from the MARA table:

abap

@AbapCatalog.sqlViewName: 'ZCDSVIEW'

@AbapCatalog.compiler.compareFilter: true

@AbapCatalog.preserveKey: true

@AccessControl.authorizationCheck: NOT_REQUIRED

@EndUserText.label: 'simple cds view'

define view zcds_view1 as select from mara

{

key mara.matnr,

mara.mtart

}

- The annotation @AbapCatalog.sqlViewName specifies that a corresponding SQL view named 'ZCDSVIEW' will be created in SE11.

- The key fields mara.matnr and mara.mtart are selected from the MARA table.

Steps to Create a CDS View

To create a CDS view in SAP, follow these steps:

1. Open Eclipse (ADT): CDS views are created using the ABAP Development Tools (ADT) in Eclipse, not in SE80.

2. Create a New Data Definition: Go to File > New > ABAP Repository Object and select Core Data Services > Data Definition.

3. Define the CDS View: Enter the annotations, source table, and fields you want to select.

4. Activate the CDS View: Once the view is defined, activate it. The SQL view will be created automatically in the ABAP Dictionary (SE11) with the name specified in the annotation @AbapCatalog.sqlViewName.

How CDS Views Appear in the ABAP Dictionary (SE11)

When a CDS view is created and activated, the name specified in the @AbapCatalog.sqlViewName annotation is used to create a corresponding SQL view in the ABAP Dictionary (SE11). This allows the CDS view to be treated like any other database view in SAP.

Types of CDS Views

1. Simple CDS View: Selects data from a single table.

2. CDS View with Joins: Combines data from multiple tables using SQL-like joins.

3. CDS View with Associations: Establishes relationships between entities without hard joins.

4. CDS View with Parameters: Accepts input parameters to dynamically filter the data.

5. Extend View: Extends an existing CDS view by adding fields.

6. Table Functions: CDS views that define database functions.

Types of CDS Views in Detail:

- Simple View: A basic CDS view that selects data from a single table.

- View with Joins: Allows you to combine multiple tables using joins.

- View with Associations: Establishes a relationship between two entities without performing an actual join until the data is queried.

- View with Parameters: Allows you to pass dynamic values into the view to filter data.

- Extend View: Used to extend the functionality of an existing CDS view by adding more fields or logic.

- Table Functions: Special CDS views that behave like database functions, returning a table based on the logic within the view.

Advantages of CDS Views over Traditional DDIC Views

- Performance: CDS views execute at the database level, taking full advantage of SAP HANA’s in-memory architecture.

- Modularization: CDS views are reusable across applications and other views.

- Code Pushdown: Heavy lifting is done by the database, not the application server.

- Flexibility: CDS views support complex joins, associations, and calculations that go beyond what traditional views offer.

Conclusion

CDS views are a powerful and flexible tool for modern data modeling in SAP. They allow ABAP developers to push down data-intensive operations to the HANA database, improving performance and enabling real-time data processing. With the advent of SAP S/4HANA and CDS views, SAP has taken a major step forward in database and application development.

CDS views are central to the new ABAP programming model, enabling high-performance, in-memory data processing. Understanding how to create, manage, and optimize CDS views is key to developing modern, efficient SAP applications.

Code Recap: