HAVING (CLAUSE)

Definition

HAVING is a SQL clause used to filter grouped results after applying GROUP BY, especially on aggregate functions like COUNT(), SUM(), AVG(), etc.

What Problem It Solves

It solves the limitation that WHERE cannot filter aggregate results, so HAVING is used for filtering group-level data.

What Happens If Not Used

You get all grouped results, even those that don’t meet conditions (e.g., all departments shown, not just high-count ones).

Easy Wording

It “filters groups after calculation.”

Technical Example

After counting students in each class, HAVING COUNT > 30 shows only large classes. SELECT department, COUNT() FROM employees GROUP BY department HAVING COUNT() > 10; Result: only departments with more than 10 employees.