Question

When we define an attribute A as PRIMARY KEY of relation R, then __________

Select one:
a. No more primary key on the relation R
b. There are no two tuples that have the same values on the A component
c. All of the others
d. Tuple must be not null on the A component

Answer 1

Defining an attribute A as a PRIMARY KEY for relation R ensures uniqueness and not null for each tuple in the A component, and enforces that there can be no additional primary key for the relation.

Step-by-step explanation:

When we define an attribute A as PRIMARY KEY of relation R, the correct response is that there are no two tuples that have the same values on the A component, and each tuple must be not null on the A component. This means that the primary key must uniquely identify each record in the database table and cannot be null. Additionally, once a primary key is defined on a relation, no other attribute can be declared as a primary key for that particular relation.