Advanced Database Management System - Tutorials and Notes: Database Management Systems (DBMS) Question Bank 04

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Sunday, 24 May 2020

Database Management Systems (DBMS) Question Bank 04

Discuss the scenarios where a view can be helpful in a database management system.


Discuss the scenarios where a view can be helpful in a database management system.

A view is a relation defined by a query and there are many benefits to views:
_ Views help provide logical data independence: That is, if applications execute queries against views, we can change the conceptual schema of the database without changing the applications. We only need to update the view definitions.
_ Views can help increase physical data independence: We can split base tables into smaller tables horizontally or vertically and hide this data organization behind a view. Also, views can be created from multiple tables or from other views, hence they help in physical data independence.
_ Views can help secure the data by limiting access to that data: We can create views that only reveal the information users are allowed to see. We can then grant users access to the views instead of the base tables. This helps in hiding the actual implementation of the base table(s).
_ Views can help encapsulate complex queries: a complex query can be written to define a view and the view name can be used to execute that complex query.
_ Views can speed-up computations if we materialize the content of a view instead of re-computing it whenever the view is used. (Materialized view is the relation generated and stored as part of executing a query. It is physically stored. On the other hand, views are not stored physically, only view definitions are stored)


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