SQL & PL/SQL :: Query For Shift Time

I'm trying to figure out, based on total scheduled shift time and scheduled breaks what the effective schedule time is by hour for a particular employee.

So I have a shift query that gives me this (using a cross-day shift here because they do happen-not sure if that will impact things):

Shift ID EmployeeID ShiftStart ShiftEnd
123 99 04/10/2013 21:00:00 04/11/2013 06:00:00

And I have a activity query that gives me

Shift ID EmployeeID ActivityStart ActivityEnd Type
123 99 04/10/2013 23:00:00 04/10/2013 23:15:00 Break
123 99 04/11/2013 02:00:00 04/11/2013 03:00:00 Lunch
123 99 04/11/2013 04:00:00 04/11/2013 04:15:00 Break

And I need a query that give me this:

Shift ID EmployeeID ShiftStart Hour Net_Scheduled_Time(min)
123 99 04/10/2013 21:00:00 04/10/2013 21:00:00 60
123 99 04/10/2013 21:00:00 04/10/2013 22:00:00 60
123 99 04/10/2013 21:00:00 04/10/2013 23:00:00 45
123 99 04/10/2013 21:00:00 04/11/2013 00:00:00 60
123 99 04/10/2013 21:00:00 04/11/2013 01:00:00 60

[Code]...

Is there a relatively easy way to get there in one query, no temp tables?