Interview Q&A / SQL & DBMS
SQL & DBMS interview questions
Joins, keys, normalisation, indexes and transactions for placement and backend interviews.
Prefer rapid revision? Practise SQL & DBMS short interview answers →
- What do the NOT NULL, DEFAULT and CHECK constraints do?
NOT NULL forbids missing values, DEFAULT supplies a value when none is given on insert, and CHECK rejects rows whose values fail a condition. Together they keep bad data out at the database level.
BeginnerQuick answer1 min read