SAP HANA Native, Create Database Artifacts Using Core Data Services (CDS)

In the db module, you will find a file called data-model.cds. Right-click on it and choose Rename.

Use the following name:

interactions.cds

Double-click on the file to open it.

Replace the default contents with the following:

namespace app.interactions;

using { Country } from '@sap/cds/common';
type BusinessKey : String(10);
type SDate : DateTime;
type LText : String(1024);


entity Interactions_Header {
  key ID : Integer;
  ITEMS  : association to many Interactions_Items on ITEMS.INTHeader = $self;
  PARTNER  : BusinessKey;
  LOG_DATE  : SDate;
  BPCOUNTRY	: Country;

};
entity Interactions_Items {

	key INTHeader : association to Interactions_Header;
	key TEXT_ID : BusinessKey;
		LANGU	: String(2);
		LOGTEXT	: LText;
};

What is going on?

You are declaring two entities with an association to each other. The design-time artifacts declared in this file will be converted to run-time, physical artifacts in the database. In this example, the entities will become tables.

Locate the other cds file (this file may be called cat-service.cds or my-service.cds, depending on the IDE) in the srv folder and rename it.

Use the following name:

interaction_srv.cds

Double-click to open it and replace the existing content with the following:

using app.interactions from '../db/interactions';
service CatalogService {

 entity Interactions_Header
	@readonly
	as projection on interactions.Interactions_Header;

 entity Interactions_Items
	@readonly
	as projection on  interactions.Interactions_Items;

}

Click Save all.

What is going on?

You are declaring services to expose the database entities you declared in the previous step.

Open the package.json file in the root of your project. Add a section to the cds configuration to include the following

"hana": {
   "deploy-format": "hdbtable"
}

Right-click on the CDS declaration of the services and choose Build > Build CDS.

Look into the console to see the progress. You can scroll up and see what has been built

If you pay attention to the build log in the console, you will see the CDS artifacts were converted to hdbtable and hdbview artifacts. You will find those artifacts in a new folder under src called gen.

You will now convert those CDS files specific to SAP HANA into runtime objects (tables). Right-click on the database module and choose Build.

Note: If you get an error during the build process, this could be caused by an older version of the XSA Runtime in HANA, express edition. If your XSA version still contains Node.js version 8.x; this can lead to errors when building because this version of Node.js is no longer supported at the OS level. Newer versions of the XSA runtime only contain Node.js version 10.x and 12.x. If you do receive an error at this point, we would suggest editing the /db/package.json like the following to force the usage of the newer version of the Node.js runtime.

{
	"name": "deploy",
	"dependencies": {
		"@sap/hdi-deploy": "^3"
	},
	"scripts": {
		"postinstall": "node .build.js",
		"start": "node node_modules/@sap/hdi-deploy/deploy.js"
	},
	"engines": {
		"node": "^10 || ^12"
	}
}

Scroll up to in the console to see what the build process has done.

What is going on?

CDS stands for Core Data Services. This is an infrastructure that allows you to create persistency and services using a declarative language. Notice how you are using the same syntax to define both the persistency and the services.
 
You can find more information on CDS in the help

You defined a CDS artifact, this is an abstraction, a design-time declaration of the entities to be represented in a database and the services to expose them.
 

The original .cds file was translated into hdbtable, which is the SQLDDL syntax specific to SAP HANA when you saved all of the files.
 

These hdbtable files were then translated into runtime objects such as tables in the HANA database.

If you checked the services in your space, you would see the service for your HDI container.

or for the HANA Cloud trial:

You can also check the resources in your space using the resource manager in SAP Web IDE:

You can find a similar example and further context on Core Data and Services in this explanatory video

You can now check the generated tables and views in the database explorer. Right-click on the database module and select Open HDI Container.

Once open, navigate to the Tables section and double-click on the Header table.

Note the name of the table matches the generated hdbtable artifacts. You will also see the physical schema managed by the HDI container.

Unless a name is specified during deployment, HDI containers are automatically created with names relative to the project and user generating them. This allows developers to work on different versions of the same HDI container at the same time.

Download the header file and the items file into your local file system.

Right-click again on the header table and choose Import Data.

Browse for the Header file and click Step 2.

Keep the default table mapping and click Step 3.

Click Show Import Summary.

And then Import into Database.

You will see confirmation that 3 records have imported successfully.

Repeat the process with the Items.csv file into the Items table.

You can now check the data loaded into the tables. Right-click on the Items table and click Generate Select Statement.

Add the following WHERE clause to the SELECT statement and execute it to complete the validation below.

where "LOGTEXT"  like '%happy%';