SQL Interview Questions and Answers — 50+ Questions
Basic SQL Questions
1. What is the difference between WHERE and HAVING?
WHERE filters rows before GROUP BY. HAVING filters groups after GROUP BY.
2. What is a PRIMARY KEY?
A column that uniquely identifies each row. Cannot be NULL or duplicate.
3. What is the difference between DELETE and TRUNCATE?
DELETE: Can use WHERE, logged, can rollback. TRUNCATE: Removes all rows, faster, cannot rollback.
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