What is a view?
A view is a tailored presentation of the data contained in one or more tables
(or other views). Unlike a table, a view is not allocated any storage space, nor
does a view actually contain data; rather, a view is defined by a query that
extracts or derives data from the tables the view references. These tables are
called base tables.
Views present a different representation of the data that resides within the
base tables. Views are very powerful because they allow you to tailor the
presentation of data to different types of users.
Views are often used to:
=> provide an additional level of table security by restricting access to a
predetermined set of rows and/or columns of a table
=> present the data in a different perspective from that of the base table
=> simplify commands for the user
=> isolate applications from changes in definitions of base tables
=> hide data complexity
=> express a query that cannot be expressed without using a view
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