Problem Statement

Question 35 Given two relations R(A,B) and S(B,C), which operations are valid? R ∪ S R × S R ⋈ S π A (R) Select your answer to the problem below: 2,3,4 1,2,3 4,3,1 1,2,4 Question 36 Entity 'student' participates in two relationships: 'Enrolls(Student, Course)' (M-N) 'MentoredBy(Student, Professor)' (1-N from Professor). How many total relations appear after mapping? Select your answer to the problem below: 4 5 6 3 Question 37 In a three-tier database system, the application layer sits between the client and the database. Which of the following statements are correct? The middle tier handles business logic and API calls. Connection pooling and transaction coordination occur in the middle tier. Clients directly manage database files. The three-tier design improves scalability and security. Select your answer to the problem below: 1, 4, 3 2, 3, 4 1, 2, 4 1, 2, 3 Question 38 In write-ahead logging (WAL): Log records are written before database updates Undo and Redo oper