Cheatsheet Pages / SQL Cheatsheet
HAVING vs WHERE in SQL — filtering groups, not rows
You want to keep only the groups whose aggregate passes a threshold, such as departments averaging over 60000.
Every example runs against the cheatsheet's sample tables — departments(id, name), employees(id, name, dept_id, salary, manager_id, hired_on) and orders(id, emp_id, amount, ordered_on) — and was executed and verified against SQLite, so you can paste it in and get the same result.
SELECT dept_id, AVG(salary) AS avg_salary FROM employees GROUP BY dept_id HAVING AVG(salary) > 60000;
-- Only dept 1 (101000) and dept 2 (70000) survive
-- WHERE filters rows before grouping; HAVING filters groups after. Don't mix them up