If we are using aggregation, do we need a HAVING clause?

A HAVING clause is used to filter groups after aggregation, whereas a WHERE clause filters rows before aggregation. You only need a HAVING clause when you want to impose a condition on an aggregate function, such as COUNT, SUM, AVG, etc. For example, SELECT department, COUNT() FROM employees GROUP BY department HAVING COUNT() > 10; filters out departments with fewer than 10 employees. If your condition involves only non-aggregated columns, you can use WHERE. If the condition references an aggregate, HAVING is required. In many cases, you might not need a HAVING clause at all if you are simply selecting aggregated values without any filtering on those aggregates.