Total salary from a hierarchical sql query in Oracle - sql

Question

I am trying to find the total salary by using oracle hierarchical SQL query but I do not get the desired output.
I use Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit.
Below are the sample input tables and the hierarchical structure.
Below is the desired output table.
Below is the code I wrote but its not summing up at all levels.
SELECT COALESCE(e.Manager_id, e.Employee_id) Employee_id,
(SELECT Employee_name
FROM Employee_table
WHERE Employee_id = COALESCE(Manager_id, Employee_id)) Employee_name,
SUM(s.Employee_salary)
FROM Employee_table e
JOIN Salary_table s
ON s.Employee_id = e.Employee_id
WHERE CONNECT_BY_ISLEAF = 1
CONNECT BY PRIOR s.Manager_id = s.Employee_id
GROUP BY COALESCE(e.Manager_id, e.Employee_id)
ORDER BY SUM(s.Employee_salary) DESC;
What am I doing wrong here?

Answer 1

Here is on approach using a standard recursive query rather than Oracle specific connect by syntax:
with cte (employee_id, employee_name, child_id) as (
select employee_id, employee_name, employee_id from employee where manager_id is null
union all
select c.employee_id, c.employee_name, e.employee_id
from employee e
inner join cte c on e.manager_id = c.child_id
)
select c.employee_id, c.employee_name, sum(s.employee_salary) total_salary
from cte c
inner join salary s on s.employee_id = c.child_id
group by c.employee_id, c.employee_name
order by c.employee_id
The recursive query starts from employees that have no manager, and retrieves the children record of each node. Then, the outer query brings the salary table, and aggregate by "root employee".
Demo on DB Fiddle:
EMPLOYEE_ID | EMPLOYEE_NAME | TOTAL_SALARY
----------: | :------------ | -----------:
1 | John | 4000
2 | Philip | 17900
9 | Joe | 5700

Answer 2

with Salary_table (Employee_id, Employee_salary) as (
select 1, 4000 from dual union all
select 2, 2500 from dual union all
select 4, 3400 from dual union all
select 5, 4500 from dual union all
select 6, 4300 from dual union all
select 7, 2000 from dual union all
select 8, 1200 from dual union all
select 9, 3100 from dual union all
select 11, 2600 from dual
)
, Employee_table (Employee_id, Employee_name, Manager_id) as (
select 1, 'John', null from dual union all
select 2, 'Phil', null from dual union all
select 3, 'Rayan', 2 from dual union all
select 4, 'Peter', 2 from dual union all
select 5, 'Mark', 2 from dual union all
select 6, 'Steve', 3 from dual union all
select 7, 'Margret', 3 from dual union all
select 8, 'Paul', 3 from dual union all
select 9, 'Joe', null from dual union all
select 10, 'Bose', 9 from dual union all
select 11, 'Jane', 9 from dual
)
select mgr_id, mgr_name, sum(employee_salary) from (
select employee_id, connect_by_root employee_id mgr_id,
connect_by_root employee_name mgr_name
from
employee_table e
start with manager_id is null
connect by prior employee_id = manager_id
)
join salary_table
using(employee_id)
group by mgr_id, mgr_name
order by 1;
MGR_ID MGR_NAM SUM(EMPLOYEE_SALARY)
---------- ------- --------------------
1 John 4000
2 Phil 17900
9 Joe 5700