SQL for Product Managers
Foundations and Technical Fluency
1. Explain what SQL is to someone with no technical background.
A strong answer avoids jargon and lands on "a precise way of asking a database a question," ideally with a concrete example.
2. What's the difference between a primary key and a foreign key?
Look for a clear, correct definition of both and, ideally, a real example connecting two tables.
3. Walk me through the difference between INNER JOIN and LEFT JOIN, and give a real scenario where using the wrong one would produce a misleading number.
Tests both syntax knowledge and the product judgment to know why the choice matters, not just what the keywords mean.
4. What does GROUP BY actually do, in plain English?
Strong answers describe collapsing rows into buckets and applying an aggregate within each bucket, not just "it groups things."
5. What is a NULL value, and why can't you filter for it with a normal equals sign?
Tests understanding of one of SQL's most common silent-failure traps.