UGC NET CSE | January 2017 | Part 2 | Question: 18

Question

Let $M$ and $N$ be two entities in an $E-R$ diagram with simple single value attributes. $R_{1}$ and $R_{2}$ are two relationship between $M$ and $N$, where as $R_{1}$, is one-to-many and $R_{2}$, is many-to-many.

The minimum number of tables required to represent $M, N, R_{1}$, and $R_{2}$, in the relational model are ___________.

• A. $4$
• B. $6$
• C. $7$
• D. $3$

Comments

Total four table required.

M, (n,r1),n,(m,n,r2)

for R1 we don't need any table as we can put the relation on N side.

for R2 we need a separate table.

 

correct me if am wrong

Answer 1

ANS : D

For many-to-many relationships there will always be a separate table and that table can not be merged with another entity.Primary key will be the combination of the primary keys of the participating entities

2+1= 3