SQL Interview Questions

The SQL concepts that come up most often in technical interviews and screening rounds, answered directly with examples.

• What is the difference between SQL's WHERE and HAVING clauses?
• What is a primary key in SQL?
• What is the difference between INNER JOIN and LEFT JOIN in SQL?
• What is normalization in SQL databases?
• What is the difference between DELETE and TRUNCATE in SQL?
• What is the difference between a clustered and non-clustered index in SQL?
• What is a subquery in SQL?