View

A view is the result of a SQL query stored in the Oracle data dictionary. One can think of a view as a virtual table or presentation of data from one or more tables. Views are useful for security and information hiding, but can cause problems if nested too deep. View details can be queried from the dictionary by querying either USER_VIEWS, ALL_VIEWS or DBA_VIEWS. Can perform DML operations on simple view(Does not contains GROUP BY clause, CONNECT BY clause, JOINS, sub query or snapshot of operations). Cannot perform DML operations on complex view(Contains atleast anyone of the above).

Advantages

• Provide an additional level of table security, by restricting access to a predetermined set of rows and columns of table.
• Hide data complexity.
• Simplify commands for the user.
• Present the data in different prespective from the base table.
• Stores complex queries