Must be MySQL

You are given a table employee containing information about employees and the department they work in. Write a query to find the number of employees that are assigned to a department. The final output column should be labeled count_employees Input Format Column Type employee no employee_name string department no int salary manager no int int int Sample Input: employee table employee_no employee_name department_no salary manager_no 10001 10002 10003 10004 10005 10006 Colt A. Juarez Damian B. Gay Darius B. Patterson Price F. Schneider Palmer W. Byrd Quyn W.Cain 99001 99005 99003 99005 99004 NULL 3244 20001 3312 20002 3401 20001 3312 20003 3653 20005 4209 20001