What is the database layer in SAP's 3-tier architecture?

The database layer is the bottom tier — where all of the system's persistent data actually lives: master data (customers, materials, vendors), transactional data (sales orders, financial postings), and the system's own configuration and program repository (in the case of ABAP-based systems). The application layer reads from and writes to this layer, but end users never interact with it directly.

//  conceptually: Application Layer issues Open SQL statements
//  that the database layer executes against actual stored tables
SELECT * FROM kna1 WHERE land1 = 'US'.   " ABAP Open SQL, runs against the database layer

Modern SAP systems (S/4HANA) run this layer on SAP's own HANA in-memory database, though classical SAP ERP systems could run on various supported third-party databases (Oracle, SQL Server, DB2, and others), with the same application layer logic working regardless of which specific database was underneath, thanks to Open SQL's database-independent syntax.

Invest now in Acorns!!! 🚀
Join Acorns and get your $5 bonus!

Acorns is a micro-investing app that automatically invests your "spare change" from daily purchases into diversified, expert-built portfolios of ETFs. It is designed for beginners, allowing you to start investing with as little as $5. The service automates saving and investing. Disclosure: I may receive a referral bonus.

Invest now!!! Get Free equity stock (US, UK only)!

Use Robinhood app to invest in stocks. It is safe and secure. Use the Referral link to claim your free stock when you sign up!.

The Robinhood app makes it easy to trade stocks, crypto and more.

Webull! Receive free stock by signing up using the link: Webull signup.