Mixing together Connect by, inner join and sum with Oracle
- by François
Hey there,
I need help with a oracle query. Excuse me in advance for my english.
Here is my setup:
I have 2 tables called respectively "tasks" and "timesheets". The "tasks" table is a recursive one, that way each task can have multiple subtasks. Each timesheet is associated with a task (not necessarily the "root" task) and contains the number of hours worked on it.
Example:
Tasks
id:1 | name: Task A | parent_id: NULL
id:2 | name: Task A1 | parent_id: 1
id:3 | name: Task A1.1 | parent_id: 2
id:4 | name: Task B | parent_id: NULL
id:5 | name: Task B1 | parent_id: 4
Timesheets
id:1 | task_id: 1 | hours: 1
id:2 | task_id: 2 | hours: 3
id:3 | task_id:3 | hours: 1
id:5 | task_id:5 | hours:1
...
What I want to do:
I want a query that will return the sum of all the hours worked on a "task hierarchy". If we take a look at the previous example, It means I would like to have the following results:
task A - 5 hour(s) | task B - 1 hour(s)
At first I tried this
SELECT TaskName, Sum(Hours) "TotalHours"
FROM (
SELECT replace(sys_connect_by_path(decode(level, 1, t.name), '~'), '~') As TaskName,
ts.hours as hours
FROM tasks t INNER JOIN timesheets ts ON t.id=ts.task_id
START WITH PARENTOID=-1
CONNECT BY PRIOR t.id = t.parent_id
)
GROUP BY TaskName Having Sum(Hours) > 0 ORDER BY TaskName
And it almost work. THe only problem is that if there are no timesheet for a root task, it will skip the whole hieararchy... but there might be timesheets for the child rows and it is exactly what happens with Task B1. I know it is the "inner join" part that is causing my problem but I'm not sure how can I get rid of it.
Any idea how to solve this problem?
Thank you
