Question 11 :
A candidate key must uniquely identify each row.
Question 12 :
Well-structured relations encourage anomalies of data.
Question 13 :
A foreign key may be null and still adhere to the referential integrity constraint.
Question 14 :
If a relation is in third normal form, it does not need to be in second normal form.
Question 15 :
The primary key of the new relation in a many-to-many relationship is a composite key comprised of the primary keys of each of the binary entities.