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Timed mock tests and model answers written by working engineers, for every level from fresher to lead. Pick any of our 75 courses below.

Topic: Databases (SQL, PL/SQL, NoSQL, DBA). Questions are shared by related courses. View the DBA SQL and NO-SQL course → · Follow the SQL & databases roadmap →

All DBA SQL and NO-SQL interview questions at a glance+

Fresher (0–3 years): Junior DBA / Database Developer

  1. Explain DELETE, TRUNCATE and DROP.
  2. A query is slow. What do you check first?
  3. What backups would you set up for a production database?
  4. What does a primary key guarantee?
  5. Normalisation mainly reduces…
  6. An index is used to…
  7. What does ACID stand for?
  8. MongoDB stores data as…
  9. In PL/SQL, a stored procedure is…

Mid-level (3–8 years): DBA / Database Engineer

  1. Design high availability for a critical MySQL/PostgreSQL database.
  2. The database CPU is at 100%. How do you investigate?
  3. When would you choose NoSQL over a relational database?
  4. Which isolation level prevents dirty reads but allows non-repeatable reads?
  5. Replication for read scaling uses…
  6. A covering index…
  7. In PL/SQL, BULK COLLECT and FORALL are used to…
  8. Redis is typically used as…
  9. Deadlocks happen when…

Experienced (8–15 years): Senior DBA / Data Architect

  1. Plan a migration from Oracle to PostgreSQL.
  2. Design a database strategy for an app growing 10× in a year.
  3. How do you secure databases containing personal data?
  4. Zero-downtime schema change on a huge table uses…
  5. Scaling writes beyond one server usually requires…
  6. RPO 0 for a database across data centres needs…
  7. CAP theorem says during a network partition you choose…
  8. Moving databases to managed cloud services mainly shifts…
  9. DynamoDB / Cassandra data modelling starts from…