Dynamic calculations in a materialized view

Question

Hi,
I have a problem. I created a materialized view which works perfectly. But now I need to perform some calculations with the data in my view . The view contains the working hours of employees who worked in different projects. Every project has a fixed amount of time (time_available) in which the employee has to finish the project. I aggregated the working hours to month for better presentation. What I want to accomplish here is a "simple" subtraction of "fixed amount for a project" minus "working hours" for the employee.
The problem here is that some project have duration of more that just one month. Naturally all my values are in one tuple for every month. So when I have 3 month of working hours for a project my view looks like this:
MV_Working_Hours:
Project --- Time_Available --- DATE --- Employee --- Working Days
Project A --- 50 Days --- 2011-05 --- Mr. A --- 15 Days
Project A --- 50 Days --- 2011-06 --- Mr. A --- 16 Days
Project A --- 50 Days --- 2011-07 --- Mr. A --- 16 Days
What I want to do is to calculate the remaining days like this :
Project --- Time_Available --- DATE --- Employee --- Working d in Month ---reaming days
Project A --- 50 Days --- 2011-05 --- Mr. A --- 15 Days --- 35 Days
Project A --- 50 Days --- 2011-06 --- Mr. A --- 16 Days --- 19 Days <--- I get here 34 which is for my need wrong !!!
Project A --- 50 Days --- 2011-07 --- Mr. A --- 16 Days --- 3 Days
Is there a way to realize this with "just" sql or do I have to use pl/sql in the OWB? I use the OWB version 11gR2
thx

Answer 1

For everybody who is confronted with the same problem I have - here is the solution: (thx to "spencer7593" and "Justin Cave" from StackOverflow)
SUM( "Working Days" )
OVER (PARTITION BY "Product", "Employee"
ORDER BY "DATE"
ROWS UNBOUNDED PRECEDING)
and please check out the link from oracle for _"SQL for Analysis and Reporting"_: http://download.oracle.com/docs/cd/E14072_01/server.112/e10810/analysis.htm