Question

Q 5 A relation, say r1, may include among its attributes primary key of another relation, say r2. r1 is also known as

Answer 1

5 A relation, say r1, may include among its attributes primary key of another relation, say r2. r1 is also known as:

In the above scenario, the attribute in r1 may also be called a 'Foreign Key'.

• A foreign key is generally used to link two separate tables. Both of the tables might have unique keys (column), they are called Primary Keys. Now, a Primary Key in one table might also be a column in the second table. But, in this second table, it will be known as a Foreign Key.

• In the above scenario, r1 finds a reference of a primary key of the relation r2. So, this reference will be a Foreign Key.