What is a view? How it is related to data independence ?

Answer 1

A View is a "Virtual Table". It is not like a simple table, but is a virtual table which contains columns and data from different tables (may be one or more tables). A View does not contain any data, it is a set of queries that are applied to one or more tables that is stored within the database as an object. After creating a view from some table(s), it used as a reference of those tables and when executed, it shows only those data which are already mentioned in the query during the creation of the View.

As view does not depend on data, it only depend upon underlying table, it is called as data independent.

Answer 2

A view may be thought of as a virtual table, that is, a table that does not really exist in its own right but is instead derived from one or more underlying base table. In other words, there is no stored file that direct represents the view instead a definition of view is stored in data dictionary.

Growth and restructuring of base tables is not reflected in views. Thus the view can insulate users from the effects of restructuring and growth in the database. Hence accounts for logical data independence.