DATABASE SYSTEM CONCEPTS (LOOSELEAF)
7th Edition
ISBN: 9781260515046
Author: SILBERSCHATZ
Publisher: MCG
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Expert Solution & Answer
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...
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Chapter 2 Solutions
DATABASE SYSTEM CONCEPTS (LOOSELEAF)
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