Chapter 2, Problem 12E

Explanation of Solution

a.

Primary Key:

• A primary key is a special column of a relation used for uniquely identifying a relation.
• The primary key can be one column or combination of columns. The primary key will uniquely identify all the records of a table.
• The features of a primary are:
  • The primary key contains a unique value for each row of data.
  • The primary key column cannot contain null values.

The appropriate primary keys for each relation:

Relation name	Primary key
branch	branch_name
customer	customer_name
loan	loan_number
borrower	customer_...

Explanation of Solution

b.

Foreign key:

• A foreign key is an attribute/column which is used for establishing relationship between two tables/relations.
• A foreign key must be primary key of the table to which it is referring.

The appropriate foreign keys are as follows:

Relation name	Foreign key
loan	branch_name
borrower	customer_name, loan_number
account	branch_name
depositor	customer_name, account_number

Explanation:

• In loan relation, branch_name is a foreign key...