Explain 2NF and 3NF — why normalize?

2NF and 3NF

For Explain 2NF and 3NF — why normalize, interviewers listen for a crisp definition, how the pieces interact in a real system, and one trade-off or failure mode you have seen or would guard against.

• 2NF: no partial dependency on composite key (all non-key cols depend on whole key).
• 3NF: no transitive dependency (non-key → non-key).
• Goal: reduce update anomalies—change professor name in one place.