Entities
are represented by means of their properties, called attributes. Attributes are
characteristics of an entity. An entity may have many attributes. For each
attribute, there is set permitted values called domain
Types
of Attributes
ATOMIC ATTRIBUTE
An
attribute that cannot be divided into smaller independent attribute is known as
atomic
attribute.
For
example, assume Student is an entity
and its attributes are Name, Age,
Address and Phone no. Here the age (attribute) of student (entity) cannot
further divide. In this example age is atomic
attribute.
COMPOSITE ATTRIBUTE
An
attribute that can be divided into smaller independent attribute is known as composite
attribute.
For
example, assume Student is an entity
and its attributes are Name, Age,
Address and Phone no. Here the address (attribute) of student (entity) can be
further divide into House no, city and so on. In this example address is atomic attribute.
SINGLE VALUED
ATTRIBUTE
An
attribute that has only single value for an entity is known as single
valued attribute.
For
example, assume Student is an entity
and its attributes are Name, Age,
Address and Phone no. Here the age (attribute) of student (entity) can have only
one value. Here, age is single valued
attribute.
MULTI VALUED ATTRIBUTE
An
attribute that can have multiple values for an entity is known as multi
valued attribute.
For
example, assume Student is an entity
and its attributes are Name, Age,
Address and Phone no. Here the Phone no (attribute) of student (entity) can
have multiple value because a student may have many phone numbers. Here, Phone
no is multi valued attribute.
STORED ATTRIBUTE
An
attribute that cannot be derived from another attribute is known as stored
attribute.
For
example, birth date cannot derive from age of student.
DERIVED ATTRIBUTE
An
attribute that can be derived from another attribute is known as derived
attribute.
For
example, age can be derived from birth date of student.
NULL VALUED ATTRIBUTE
An
attribute, which has not any value for an entity is known as null
valued attribute.
For
example, assume Student is an entity
and its attributes are Name, Age,
Address and Phone no. There may be chance when a student has no phone no. In that
case, phone no is called null valued
attributes.
KEY ATTRIBUTE
An
attribute that has unique value of each entity is known as key attribute.
For
example, every student has unique roll no. Here roll no is key attribute.
Great work...
ReplyDeleteWell Answered
DeleteThe example of derived attribute is wrong
ReplyDeleteerror in writting
DeleteExample of derived value is age can derived from birthdate
ReplyDeleteIn derived attribute age can be derived from birth date
ReplyDeleteBut birth date cannot be derived from age
DeleteNice notes
ReplyDeleteTq for the information
ReplyDeleteCheck composite attribute's last line
ReplyDeletevery nice post on types of attributes
ReplyDeleteVery nice notes,check on derived attribute.otherwise the others are correct and understandable.nice examples too.
ReplyDeleteunderstandable notes thanks
ReplyDeleteDerived attribute example is wrong
ReplyDeleteNICE
ReplyDeleteEr diagrams allows attributes to be assigned on relationships so what is the name of that attribute ?
ReplyDeleteVery useful
ReplyDeletechange atomic to composite in composite attribute last line
ReplyDeleteWhy 'Key Attribute' is all covered in white colour?? 🤔
ReplyDeleteTHANK U
ReplyDelete