Explanation:The attributes name , street and department can repeat for some tuples.But the id attribute has to be unique .So it forms a primary key. 6. Which one of the following cannot be taken as a primary key ?
A. Id
B. Register number
C. Dept_id
D. Street
Answer:A
Explanation:The attributes name , street and department can repeat for some tuples.But the id attribute has to be unique .So it forms a primary key. 6. Which one of the following cannot be taken as a primary key ?
A. Id B. Register number C. Dept_id D. Street
Explanation:Street is the only attribute which can occur more than once. 7. A attribute in a relation is a foreign key if the _______ key from one relation is used as an attribute in that relation .