Multiple counts in a single statement

Question

Hi,
I am trying to get a total count of the number of employees in departments as well as the total numbers in specific salary ranges and display it all in one set of results.
Here is the code I have so far:
select distinct e.department_id,
ct1.subct+ct2.subct+ct3.subct+ct4.subct total_num,
ct1.subct,
ct2.subct,
ct3.subct,
ct4.subct
from employee e,
(select department_id, count(department_id) subct from employee where salary < 1500 group by department_id) ct1,
(select department_id, count(department_id) subct from employee where salary >= 1500 and salary <=2499 group by department_id) ct2,
(select department_id, count(department_id) subct from employee where salary >= 2500 and salary <=3499 group by department_id) ct3,
(select department_id, count(department_id) subct from employee where salary >= 3500 group by department_id) ct4
where e.department_id=ct1.department_id
and e.department_id=ct2.department_id
and e.department_id=ct3.department_id
and e.department_id=ct4.department_id
The problem with this code is that it only displays departments which have at least one employee in each of the salary ranges in the results. This is because of the join statements, I know, but is there any way around it?
I know there are some alternative approaches altogether to this problem, using the likes of ROLLUP and so on, but I would like to do it using essentially a similar method to my code above, if that is in fact possible.
Any assistance would be appreciated!

Answer 1

Can yu use ROLLUP..?
SQL> select d.deptno,case when sal < 1500 then 'Low'
  2                       when sal between 1500 and 3000 then 'Medium'
  3                       when sal is null then 'No emp'
  4                       else 'High'
  5                   end sal_range,count(empno)
  6  from dept d,emp e
  7  where d.deptno = e.deptno(+)
  8  group by rollup(d.deptno,case when sal < 1500 then 'Low'
  9                       when sal between 1500 and 3000 then 'Medium'
10                       when sal is null then 'No emp'
11                       else 'High'
12                   end);
    DEPTNO SAL_RA COUNT(EMPNO)
        10 Low               1
        10 High              1
        10 Medium            2
        10                   4
        20 Low               2
        20 Medium            3
        20                   5
        30 Low               3
        30 Medium            3
        30                   6
        40 No emp            0
    DEPTNO SAL_RA COUNT(EMPNO)
        40                   0
        45 No emp            0
        45                   0
                            15
15 rows selected.