Identification of Attributes

 

Introduction of Attributes

An attributes is a property or characteristic of an entity. An entity may contain any number of attributes . One of the attribute considered as the primary Key. Also we can explain like this, Attributes is entity are represented by means of their properties called attributes. In an entity-relational model, are represented in an elliptical shape.

 

All attributes have values. There are several types of attribute in ER-modal.

Types of Attributes

Ø Simple Attributes ­: Simple attributes are atomic value, which cannot be                    further. For an example, a student phone number is an atomic value of 10 digits.

Ø Composite Attributes : An attributes that can be split into components is a composite attributes.

Ø Single-valued  Attributes : The attribute which takes up only a single value for each entity instance is a single-valued attributes. For an example, the age of a student.

Ø Multi-valued Attributes : The attributes which takes up only a single value for each entity instance is a multi-valued attributes. For an example, phone number of student: landline and mobile.

Ø Derived Attributes : An attributes that can be derived form other attributes is derived attributes. For an example, total and average mark of student.