Question: SQL Databases Consider the following relational schema: course(courseID, deptName) //CourseID is the key enroll(studentID,courseID) // is the key Suppose there are three types of queries

SQL Databases

Consider the following relational schema:

course(courseID, deptName) //CourseID is the key enroll(studentID,courseID) // is the key Suppose there are three types of queries commonly asked on this schema:

(1) Given a courseID, find the name of the department offering that course. (2) Find all students together with all of the departments they are taking courses in; i.e., effectively take the natural join of enroll and course. (3) Given a studentID, find all courses the student is enrolled in.

Questions:

(a) What is the minimal number of indexes needed to speed up all three types of queries?

(b) On which attributes should these indexes be created?

Helpful tip: Before answering, write down the queries for (1), (2), and (3).

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