Views:
Views are a tailored presentation of the data contained in one or more views or tables. A view takes the output of a query and displays it. The Views holds queries that are selected from one or more tables or in turn views itself. These are known as Base tables. Views give the following benefits:
The Restricted Access to specific columns of a table thus providing further security. They cover or hide data complexity. They are used to simplify commands because the queries which are issued very often can be placed inside a view and the view can just be selected.
A Direct DML operation is possible on Views with some restrictions.
On the bases on the query contained in the definition of a view, the Views can be classified into three types