Question

Which relation is created with primary key and non-key attributes only?

A) Regular entity
B) Weak entity
C) Sub-type
D) Associative entity

Answer 1

The relation created with a primary key and non-key attributes only is a weak entity.

Step-by-step explanation:

The relation that is created with a primary key and non-key attributes only is a weak entity. A weak entity is an entity that does not have enough attributes to form a primary key on its own.

For example, consider a database for a library. The 'Book' entity may have attributes such as 'ISBN,' 'Title,' and 'Author.' However, when representing 'Loan' entities, which track the borrowing of books by users, the 'Loan' entity may not have a unique identifier by itself. It may need to rely on the combination of a foreign key referencing the 'Book' entity and additional attributes like 'Loan Date' to create a primary key.