I have these tables that need to be addressed in this query:

Requests      Prerequisites      Courses
--------      -------------      -------
ID            CourseID           ID
EmployeeID    PrerequisiteID     Name
CourseID
StatusID

The reqeusts table is a list of all the requests coming in from employees for courses. A course can have zero or more prerequisites therefor the prerequisites table would have data similar to the following:
CourseID 1 1 1 2 2 4 5 5 5
PrerequisiteID 2 3 4 3 4 6 3 4 6
Note: PrerequisiteID is also a link to the courses table.

The result I am trying to get from a query is for each request show what prerequisites the employee has completed and what ones the employee still needs to complete.

eg.

Request    Employee   Course   Prereq    Completed
1          2          1        2         0
1          2          1        3         0
1          2          1        4         1
2          2          2        3         0
2          2          2        4         1
3          2          3                           
4          3          1        2         1
4          3          1        3         1
4          3          1        4         1

Any help would be greatly appreciated. TIA.