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. |
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