Core Data Services (CDS) views are an essential part of SAP's modern data modeling infrastructure. They allow you to define data models directly on the database layer, enabling faster data processing and efficient application development. In this blog, we will go over the important points of creating a CDS view, highlighting its significance and how it fits into the modern SAP landscape. This guide focuses on the concept, so you can add your own code and screenshots for the actual implementation.
Difference between Dictionary views and CDS views:
|
Dictionary Views |
CDS views |
|
Cannot perform calculations,
aggregations, grouping |
Can perform calculations,
aggregations, grouping |
|
Limited support for
joins |
Vast Support for
Joins and Unions |
|
Doesn’t support
nested views |
Support nested
views(view on view) |
|
DB view consumption
takes place at application server level |
Executed at Hana
Database level |
|
Can be developed on
SE11 – ABAP Dictionary |
Can be created in
HANA Studio |
What is a CDS View?
CDS (Core Data Services) views are used to define and consume data models directly at the database level. Unlike traditional ABAP Dictionary views, CDS views go beyond data retrieval and allow complex data modeling with annotations, associations, and calculated fields, making them ideal for SAP S/4HANA applications.
I’m creating CDS view in local object.
Navigation or steps:
Local object -> New -> Other ABAP Repository Object
-> Core data services -> Data definition -> give name and description
-> I’m creating local object so no need to select TR -> Click define view
-> finish
Code:
@AbapCatalog.sqlViewName:
'ZCDSVIEW3'
@AbapCatalog.compiler.compareFilter:
true
@AbapCatalog.preserveKey:
true
@AccessControl.authorizationCheck:
#NOT_REQUIRED
@EndUserText.label: 'Sample
cds view'
define view zcds_view3 as select
from kna1
{
kunnr as customerno,
case land1
when 'IN' then 'INDIA'
when 'US' then 'UNITED
STATES'
when 'DE' then 'GERMANY'
else 'OTHER' end as
Country,
name1 as CustomerName,
ort01 as city
}
Key Points:
- Integration with HANA: CDS views take advantage of the
power of SAP HANA by pushing the logic down to the database.
- Reusable: Once a CDS view is created, it can be reused
in multiple applications and reports, reducing redundancy.
- VDM (Virtual Data Model): CDS views form the foundation
of the Virtual Data Model (VDM), a key architecture element in SAP S/4HANA.
- Annotations: CDS views support annotations, which allow
additional metadata to be embedded, making them highly flexible and
customizable.
Important Features
of CDS Views
1. Efficient Data Modeling:
CDS views allow
for efficient data retrieval by pushing the logic to the database, which
minimizes data transfer between the application and database layer.
2. Declarative Syntax:
CDS views use a
SQL-like declarative language, which makes them easy to write and understand.
3. Annotations:
Annotations are
key-value pairs that extend the functionality of the view. For example,
annotations can define whether the view should be visible to end users or
specify security restrictions.
4. Associations:
CDS views
support associations between different entities, which allow for more complex
queries without the need for manual joins.
5. Enhancing Existing Models:
Existing CDS
views can be extended without modifying the original definition. This is useful
for adding fields or annotations based on evolving business requirements.
6. Types of CDS Views:
- Basic View: A
simple view that pulls data from a table or multiple tables.
- View with
Associations: Allows you to define relationships between different entities.
- Parameterized
View: Enables passing of parameters to filter data.
- Table
Functions: Advanced CDS views that incorporate logic into the data model.
CDS View Creation
Process Overview
Here’s a quick overview of the steps involved in creating
a CDS view:
1. Open SAP HANA Studio or ABAP Development Tools (ADT).
2. Create a new CDS View:
- Navigate to
Local Object → New → Other ABAP Repository Object.
- Choose Core
Data Services → Data Definition.
- Provide a name
and description.
- Define the
view by specifying the source tables and fields.
3. Activate the View: Once the view is activated, it
generates a SQL view in the SAP database.
4. Test the CDS View: Execute the view and verify that
the data is populated as expected.
Interview Questions
1. What is the main advantage of CDS views over
traditional ABAP Dictionary views?
CDS views allow
complex data modeling, filtering, and aggregation directly at the database
level. This reduces the load on the application server and speeds up data
retrieval, especially with SAP HANA.
2. What is the role of annotations in CDS views?
Annotations
extend the functionality of CDS views by adding metadata. They can control
behavior like security restrictions, data exposure, and how the view integrates
with other components like SAP Fiori.
3. Explain the difference between a standard view and a
CDS view.
A standard view
is created in the Data Dictionary (SE11) and has limited functionality. CDS
views, on the other hand, are created directly in the ABAP layer, allowing for
more complex queries, associations, and the use of annotations.
4. What are associations in CDS views, and how are they
different from joins?
Associations
represent relationships between different entities in a CDS view. Unlike joins,
associations are lazy-loaded and only processed when accessed, which improves
performance.
5. What is a parameterized CDS view?
A parameterized
CDS view allows you to pass parameters when executing the view. This is useful
when you want to filter the data dynamically based on input values.
6. Can you modify an existing CDS view without changing
the original code?
Yes, CDS views
can be extended without modifying the original definition using the extend view
keyword. This allows for additional fields or annotations to be added as
needed.
7. What are the differences between a basic CDS view and
a table function?
A basic CDS view
is primarily for reading data, while a table function is an advanced CDS view
that includes logic for data processing.