Null Attribute
This attribute can take NULL value when entity does not have value for it.
Example –The ‘Net Banking Active Bin’ attribute gives weather particular customer having net banking facility activated or not activated.
For bank which does not offer facility of net banking in customer table ‘Net Banking Active Bin’ attribute is always null till Net banking facility is not activated as this attribute indicates Bank offers net banking facility or does not offers.
Types of Attributes in ER Model
In a Database Management System (DBMS), an attribute is a property or characteristic of an entity that is used to describe an entity. Essentially, it is a column in a table that holds data values. An entity may contain any number of attributes. One of the attributes is considered as the primary key. In an Entity-Relation model, attributes are represented in an elliptical shape.
Example: Student has attributes like name, age, roll number, and many more. To uniquely identify the student, we use the primary key as a roll number as it is not repeated. Attributes can also be subdivided into another set of attributes. Attributes help define and organize the data, making it easier to retrieve and manipulate information within the database. In this article, we are going to discuss about different types of attributes in detail.