Question 3 - Past Year - 2 Mark Questions - Chapter 8 - Database Concepts

Last updated at April 16, 2024 by Teachoo

Differentiate between the primary key and alternate key of a table with the help of an example.

Answer:

Primary key refers to a set of one or more attributes which can uniquely identify tuples in a relation.
Alternate key refers to any candidate key which is not selected as the primary key.

Example:

Employee_id	Employee_name	Department	Emp_Email
101	Ravi Kumar	Sales	[email protected]
102	Tarun A	IT	[email protected]
103	Jennifer Davis	HR	[email protected]
104	Martin Woods	HR	[email protected]
105	Ron Romy	IT	[email protected]

In table employee, the candidate keys are Employee_id and Emp_Email since we can uniquely identify an employee with either of the two.

If we select Employee_id as the primary key, then Emp_Email becomes an alternate key.

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Transcript

Differentiate between the primary key and alternate key of a table with the help of an example. Answer: Primary key refers to a set of one or more attributes which can uniquely identify tuples in a relation. Alternate key refers to any candidate key which is not selected as the primary key. Example: Employee_id Employee_name Department Emp_Email 101 Ravi Kumar Sales [email protected] 102 Tarun A IT [email protected] 103 Jennifer Davis HR [email protected] 104 Martin Woods HR [email protected] 105 Ron Romy IT [email protected] In table employee, the candidate keys are Employee_id and Emp_Email since we can uniquely identify an employee with either of the two. If we select Employee_id as the primary key, then Emp_Email becomes an alternate key.

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo

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