Have to find which department have least number of employee ? and department with 2nd least number?

want to display that which department have least number of employee ? and department with 2nd least number?

there are three tables
1)departments
*dept_no
*dept_name
2)dept_emp
*emp_no
*dept_no
3)employees
*emp_no
*emp_name

how to join these tables and find which department have least number of employee ? and department with 2nd least number?

What I have tried:

i had tried the following code

SELECT d.`dept_no`,
       d.`dept_name`,
  count  (dt.emp_no) as "Num of employees"
FROM departments d
  join dept_emp dt
  on d.dept_no=dt.dept_no
  having count(dt.emp_no)=
    (select min(count(de.emp_no))
    from departments d
    join dept_emp dt
    on d.dept_no=dt.dept_no
    group by d.dept_name)
group by d.dept_name;

but its showing error something like

"You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'group by d.dept_name' at line 13"

Tags: SQL, MariaDB