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

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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

SQL

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"

Posted 31-Dec-19 0:11am

Oviya Sivakumar

Updated 31-Dec-19 0:37am

Maciej Los

v2

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OriginalGriff · Accepted Answer · 2019-12-31T00:28:00

Solution 1

Well ... "de" doesn't exist:

SQL

(select min(count(de.emp_no))

And GROUP BY needs to precede HAVING:

SQL

having count(dt.emp_no)=
...
group by d.dept_name;

But why so complicated? A simple JOIN will do it:

SQL

SELECT TOP 2 d.DeptNo, d.DeptName, de.EmpPerDept
FROM Departments d
JOIN (
SELECT DeptNo, COUNT(EmpNo) AS EmpPerDept
FROM DeptEmp 
GROUP BY DeptNo) de
ON de.DeptNo = d.DeptNo
ORDER BY EmpPerDept ASC

Posted 31-Dec-19 0:28am

OriginalGriff

v2

Comments

Oviya Sivakumar 2-Jan-20 0:44am

it works thank you

OriginalGriff 2-Jan-20 1:59am

You're welcome!