Updating relational databases through views
This can cause the number of views that must be supported and maintained to continually expand until so many views exist that it is impossible to categorize their uses.There are seven primary uses for which views excel. Security One of the most beneficial purposes served by views is to extend the data security features of SQL Server.The data "in the view" is not stored anywhere and only physically exists in the underlying tables. Views that access multiple tables can only modify one of the tables in the view.Views that use functions, specify DISTINCT, or utilize the GROUP BY clause may not be updated.These rules were developed over a number of years as a result of implementing large relational databases in many different environments.There may be more uses for views than are presented here, so do not needlessly fret if you do not see your favorite use for views covered in this articleunless you blindly use base table views.
As you read this article you will find that views are very useful when implemented wisely, but can be an administrative burden if implemented without planning.Furthermore, views are simple to create and implement.But unfortunately most users do not adhere to a systematic and logical approach to view creation.This is a requirement of the relational model and is referred to as relational closure.A view is basically the relational model's way of turning a SELECT statement into a "table" that is accessible using SQL. They can consist of any combination of the following: Views are defined using SQL and are represented internally to SQL Server by a SELECT statement, not by stored data.