Using your Oracle database, write SQL command to create the following tables and then answer each of the questions: Student(StudentId, StudentFName, StudentLName, Major, Credits) Faculty(FacultyId, FacultyName, Department, Rank) Class(ClassId, FacultyId, Timeslot, RoomNbr) Enroll(StudentId, ClassId, Grade) a. Create user Tom201 and give him permissions to read and update the student class enrollments, however he should not have access to the students grade. How can you do that

Suppose there is a relation r(a, b, c) with a b+-tree index with search keys (a, b).1. what is the worst-case cost of finding records satisfying 10 < a < 50 using this index, in terms of the number of records n1, retrieved and the height h of the tree? 2. what is the worst-case cost of finding records satisfying 10 < a < 50 and 5 < b < 10 using this index, in terms of the number of records n2 that satisfy this selection, as well as n1 and h defined above? 3. under what conditions on n1 and n2, would the index be an efficient way of finding records satisfying the condition from part (2)?