What is the purpose of using “having count” in MySQL?

In MySQL, the HAVING COUNT statement is used to filter out rows that meet certain conditions on the result of specific aggregate functions (such as COUNT) after summarizing the data. It is usually used in conjunction with GROUP BY to filter the data after grouping it.

For example, the following statement will return departments in the employees table that have more than 5 employees.

SELECT department_id, COUNT(*) as employee_count
FROM employees
GROUP BY department_id
HAVING COUNT(*) > 5;

The above query first groups the data in the employees table by department_id, then calculates the number of employees in each department, and filters out the departments with more than 5 employees using the HAVING COUNT(*) > 5 condition.