5 SQL Concepts That Commonly Catch Beginners Off Guard in Tech Interviews

A guide aimed at tech interview candidates highlights five SQL topics that appear straightforward but frequently trip up beginners. The areas covered include the difference between WHERE and HAVING clauses, the concept of composite primary keys, and how INNER JOIN behaves when no matching rows exist. The guide also clarifies why NULL comparisons require IS NULL instead of the equals operator, and explains the key distinctions between DELETE and TRUNCATE commands. Each explanation focuses on the reasoning behind SQL's behavior, which is the level of depth interviewers typically expect beyond surface-level answers.