Computer Science & IT – B.Tech, BCA, BBA, MCA, M.Tech Best Online Coaching Institute

KEYS in Database Management System

Introduction to keys

It is a part of database management system or relational database management system and important part for creating the structure of a table. They are used to establish and identify relation between tables and help how to create integrity on tables. There are various type of keys used in a database.

  1. Super Keys
  2. Candidate Keys
  3. Primary Keys
  4. Foreign Keys
  5. Alternate keys
  6. Simple Keys
  7. Compound Keys
  8. Composite Keys

Let us explain these keys with the help of an example. Consider a relation Employee, having column ID, Emp-no, Name, Designation and City.

Example of Employee table in keys

Example of Employee table in keys

Super Keys

A Set of attributes is called a super key, if it recognizes the tuple uniquely. Every relation has at least one default super key. A super key has redundant attributes.

For example: ID + Name + City is a (more…)

This content is restricted to site members. If you are an existing user, please log in. New users may register below.

Existing Users Log In
 Remember Me