Aggregation in SQL: interview exercises

Aggregation in SQL: 6 test-checked interview exercises (COUNT and SUM, GROUP BY), each beside a worked example, with tests as you go. Free.

1. COUNT and SUM
2. GROUP BY
3. Filter groups with HAVING
4. COUNT(DISTINCT ...)
5. Conditional aggregation
6. Group by month

Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Progress is saved in your browser, and in your account if you sign in.

More SQL topics

• Select & Filter
• Joins
• Subqueries & CTEs
• Window Functions
• Strings, Dates & CASE
• Modifying Data
• Schema Design

All SQL exercises · Other languages and frameworks