Database View

A view s the dynamic result of one or more relational operations operating on the base

 relations to produce another relation. A view is a virtual relation that doesn’t actually

 exist n the db but is produced upon request by a particular user, at the time of request.

Purpose of views:

  1. Security
  2. Customized access of data
  3. Simplify complex operations on base relations.

Updating views:

  1. Updates r allowed by query involving a single base relation & containing either
  2. pkey or cand key of base relation.
  3. no updates through views which involve multiple base relation.
  4. no udate through views which involves aggregation or grouping operations.