Relationship in DBMS

 Relationship in DBMS


The association among entities is called a relationship.
example, the relationship between an employee and a department is works_at.
example, relationship enrolls is used in student and course.
Relationship Set
A set of relationships of a similar type is called a relationship set. These attributes are also called descriptive attributes.

Degree of Relationship

The number of participating entities in a relationship is called the degree of the relationship.

Single or recursive = degree 1

The entity is related to itself it is known as Recursive Relationship.

Binary = degree 2

  • A binary Relationship means the relation between two Entities.
  • This is further divided into three types.
  • One to One Relationship
  • One to many Relationship
  • Many to many Relationship
 Ternary = degree 3
n-ary = degree n
A Ternary relationship involves three entities.


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