employee department wise and count of employees more than 5

Question

i want to display department_id\'s along with count,and count should be more than 5, and i want to have employees who are not hired in January.

i tried the

Answer 1

SELECT department_ID, count(employee_id) as '# of Employees' FROM EMPLOYEES 
WHERE DEPARTMENT_ID IN
 (
   SELECT DEPARTMENT_ID
    FROM EMPLOYEES
   GROUP BY DEPARTMENT_ID
   HAVING COUNT(*)>5 
 )
AND HIRE_DATE NOT LIKE '%JAN%'
group by department_ID;

This query returns the department_id and because I group by department_id, the count of employees that belong to each department will be returned

Output will look something like this

  Department_Id | # of Employees
        1             7
        2             6
        4             9

Answer 2

Select the count from your inner query and join to it:

SELECT E.*, DEPT_COUNT
FROM EMPLOYEES E
JOIN (
   SELECT DEPARTMENT_ID, COUNT(*) DEPT_COUNT
   FROM EMPLOYEES
   GROUP BY DEPARTMENT_ID
   HAVING COUNT(*) > 5 
) DC ON E.DEPARTMENT_ID = DC.DEPARTMENT_ID
AND HIRE_DATE NOT LIKE '%JAN%'

Answer 3

If you want the dept id and count of employees (where employee hire date is not in Jan) then something like the following should work. I say "something like the following" because I suspect the WHERE hire_date NOT LIKE '%JAN%' could be improved, but it would just depend on the format of that column.

   SELECT
      DEPARTMENT_ID, 
      COUNT(*) 
    FROM EMPLOYEES 
    WHERE HIRE_DATE NOT LIKE '%JAN%' 
    GROUP BY DEPARTMENT_ID 
    HAVING COUNT(*)>5;

If you also want to list the individual employees along with these departments, then something like this might work:

SELECT a.*, b.count(*) 
FROM EMPLOYEES AS a 
INNER JOIN (   
SELECT
      DEPARTMENT_ID, 
      COUNT(*) 
    FROM EMPLOYEES 
    WHERE HIRE_DATE NOT LIKE '%JAN%' 
    GROUP BY DEPARTMENT_ID 
    HAVING COUNT(*)>5) AS b
ON a.department_id = b.department_id
WHERE a.HIRE_DATE NOT LIKE '%JAN%';

Again, though, I think you can leverage your schema to improve the where clause on HIRE_DATE. A like/not-like clause is generally going to be pretty slow.