Frequently Asked Questions on Types of Attributes in ER Model-FAQs
Why attributes are used?
Attributes are used to get more information about the entity which will help to store the data in a specific format. Attributes are essential parts of the entity as all entity-related data is stored in the form of attributes only.
What is difference between stored and derived attribute?
Stored attribute does not require any update while derived attribute require update and its value is derived from other attribute. For example stored attribute is D.O.B while age is the example of derived attribute.
Can an entity have zero attributes?
Yes, the entity can have zero attributes but that entity will not carry any information with us resulting in no use of the entity.
What is an attribute in a table?
A column name is the attribute in a table.
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.