What is the difference between the use of HAVING and WHERE conditions in SQL?

In SQL, WHERE and HAVING are used for filtering, but at different stages of data processing:

• WHERE filters rows before grouping (before GROUP BY). It limits the dataset that will be aggregated.
• HAVING filters groups after aggregation. It is used for conditions on aggregate functions, such as SUM(), COUNT().

Example:

SELECT department, COUNT(*) as employee_count
FROM employees
WHERE salary > 50000  -- filter employees with salary > 50000
GROUP BY department
HAVING COUNT(*) > 10     -- select departments with more than 10 such employees

Thus, WHERE works with individual records, while HAVING works with the results of aggregation.