Explain the difference between WHERE and HAVING

WHERE

• Filters rows before data is grouped.
• Cannot use aggregate functions (SUM(), COUNT(), AVG(), etc.).
• Applies to individual records in the table.

Example:

MySQL 8.1
SELECT department_id, COUNT(*)
FROM employees
WHERE salary > 50000
GROUP BY department_id;

HAVING

• Filters groups of rows after the data is grouped.
• Can use aggregate functions.
• Applies to the results of GROUP BY.

Example:

MySQL 8.1
SELECT department_id, COUNT(*) AS num_employees
FROM employees
GROUP BY department_id
HAVING COUNT(*) > 5;