Consider the following ER diagram. Question: Which of the following is a…
2008
Consider the following ER diagram.
Question: Which of the following is a correct attribute set for one of the tables in the minimum relational schema for M, N, P, R1, and R2?
- A.
M1, M2, M3, P1
- B.
M1, P1, N1, N2
- C.
M1, P1, N1
- D.
M1, P1
Attempted by 517 students.
Show answer & explanation
Correct answer: A
Minimum number of tables: 3.
M table: M(M1, M2, M3, P1). Relationship R1 can be represented by adding P1 as a foreign key in M.
P table: P(P1, P2).
N table: N(P1, N1, N2). N is a weak entity identified through P, so P1 is included with N1 and N2; commonly (P1, N1) forms the key.
So the student concern is partly valid: N1 and N2 are included in the N table. However, among the listed options, the only complete attribute set that matches one of the minimum-schema tables is M1, M2, M3, P1.
Correct answer: M1, M2, M3, P1.