How to fetch data from one table which is not present in another table ?

Hi all,

        I am working on Attendance project ,where i have three tables 

Student:-Student_Id,Student_Rollnumber,Student_name etc 

Attendance Master:-Attendance_Master_Id,Class_Id,Faculty_Id,Subject_Id etc

Attendance Details:-Attendance_Details_Id,Attendance_Master_Id,Student_Id,Attendance(Present/Absent)

While taking attendance of  class ,1 record is inserted in attendance master and student whether=absent/present record is inserted in attendance_details using foreign key Attendance_Master_Id.

I want to retrieve student roll numbers of students in a class whose attendance are not taken ,It means students of a class whose records are not present in table Attendance_Details ,i cannot form query for stored procedure to derive this ,Please help me ,i am stuck here

Thanks

Rohit J