What is Attributes in DBMS
Attributes in DBMS
Hello friends! Today we will read about Attributes in DBMS (What is attribute?) in this post. And also see its types. Read it completely, you will understand it easily. So, let’s start: –
Attribute in dbms
In DBMS, an attribute is a property or characteristic of an entity that is distinct from other entities and provides information about that entity.
An entity can have more than one attributes. Oval is used to represent an attribute.
Types of Attributes
There are following 5 types of attributes in DBMS:-
Key attributes
The attribute that uniquely identifies each entity in the entity set is called a key attribute. For example – Roll_no is unique for each student. In ER diagram, the text of key attribute is underline.
Composite attribute
The attribute which is made of combination of other attributes is called composite attribute. For example – Student’s address is a composite attribute because it is made up of other attributes like- pin_code, city, state, and country.
Single value attribute
The attribute which has only one value for a particular entity is called single value attribute. For example- the age of a person is a single value attribute.
Multivalued attribute
An attribute that has multiple values for an entity is called a multivalued attribute. It is presented by double oval. For example:- Colors for a car and phone numbers of employees.
Derived attribute
The value of this type of attribute is derived from the value of another related attribute. It is represented by dashed oval. For example: – The age of a person is derived from his date of birth. So age is a derived attribute.
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