Difference between Stored and Derived Attribute

Prerequisite – Types of Attributes
1. Stored Attribute :
Stored attribute is an attribute which are physically stored in the database.
Assume a table called as student. There are attributes such as student_id, name, roll_no, course_Id. We cannot derive value of these attribute using other attributes. So, these attributes are called as stored attribute.

2. Derived Attribute :
A derived attribute is an attribute whose values are calculated from other attributes. In a student table if we have an attribute called as date_of_birth and age. We can derive value of age with the help of date_of_birth attribute.

Difference between Stored and Derived Attribute :

S.NO.	Stored Attribute	Derived Attribute
1.	For a stored attribute it is mandatory to be stored in the database.	For a derived attribute it is not mandatory to be stored in the database.
2.	It is not possible to determine the value of a stored attribute.	It is possible to determine the value of a derived attribute with the help of another attribute.
3.	It is an attribute that cannot be derived from any other attribute.	It is an attribute that can be derived from any other attribute.
4.	Stored attribute will be fixed.	Derived attribute will be variable in nature.
5.	Stored attribute is represented by an oval.	Derived attribute are represented by a dotted oval.
6.	Stored attribute saves the CPU’s processing cycle.	Derived attribute if not stored in Relational table, then save storage space.
7.	Stored attribute save data access time.	Derived attribute if it is not stored in the Relational table, then the data access time is longer.
8.	Stored attribute requires constant maintenance to ensure that the derived value is current.	Derived attribute if it is not stored in the Relational table, does not require maintenance, since it is derived from the stored attribute.
9.	Stored attribute does not add coding complexity to queries.	Derived attribute if not stored in the Relational table, adds coding complexity to queries.
10.	Stored attribute data value is readily available.	Derived attribute if not stored in the Relational table, data value is not readily available.