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GATE and NET questions on ER Diagram

Q: Gate – 2012, question 14

Given the basic ER and relational models, which of the following is incorrect?

a. An attribute of an entity can have more than one value.

b. An attribute of an entity can be composite.

c. In a row of a relational table, an attribute can have more than one value.

d. In a row of a relational table, an attribute can have exactly one value or a null value.

Answer: Option c is correct

Q: UGC NET 2017 question 18

Let M and N be two entities in an E-R diagram with simple single vale attributes. R1 and R2 are two relationships between M and N, whereas R1 is one-to-many and R2 is many-to-many. The minimum number of tables required to represent M, N, R1, and R2 in the relational model are _________.

A. 4

B. 6

C. 7

D. 3

Solution:

Two tables for two entities and one table for many to many relationships.

So, total 3 tables required option (d) is correct.