SQL GROUP BY With HAVING: Filter Aggregated Results

SELECT department, COUNT(*) AS headcount, SUM(salary) AS total_salary
FROM employees
GROUP BY department
HAVING SUM(salary) > 500000
ORDER BY total_salary DESC;

GROUP BY aggregates employees by department. HAVING filters to only departments where the SUM of salaries exceeds 500,000. WHERE couldn't do this because the sum doesn't exist until after grouping.

1. SELECT department, COUNT(*), SUM(salary) — what to show per group
2. FROM employees — source table
3. GROUP BY department — create one row per department
4. HAVING SUM(salary) > 500000 — filter groups by aggregate condition
5. ORDER BY total_salary DESC — show highest-spending departments first

• HAVING without GROUP BY treats the entire table as one group
• Column aliases (total_salary) may not work in HAVING in some databases — use the full expression
• NULL values in GROUP BY column create their own group
• Multiple HAVING conditions: use AND/OR like in WHERE