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IBM Db2

IBM Db2 is a long-running enterprise relational database maintained by IBM. It sits around #26 in real-world usage (roughly 2.4%) — still common on mainframes and large legacy corporate systems (banking, insurance, government), occupying a similar niche to Oracle.

📌 Quick facts
Type: Relational (SQL)
Made by: IBM
License: Paid/proprietary (with a free Community edition)
Hosting: Self-hosted (including mainframe) or cloud-managed
Primary use case: Legacy enterprise and mainframe systems already standardized on IBM's stack

Core concepts & example

Db2 uses standard SQL with IBM-specific extensions, commonly accessed via its CLI (CLP) or JDBC:

SELECT account_id, balance
FROM accounts
WHERE balance > 10000
FETCH FIRST 10 ROWS ONLY;

Getting started

IBM offers a free Community Edition for local development, most commonly run via Docker:

# run Db2 Community Edition locally via Docker
docker run -d --name db2 -p 50000:50000 -e LICENSE=accept \
  -e DB2INSTANCE=db2inst1 -e DB2INST1_PASSWORD=yourpassword \
  icr.io/db2_community/db2

🎯 Best for: legacy enterprise and mainframe systems already standardized on IBM's stack.