Is the window or view (View) external users have access to view (View) is a piece of data that a general user is interested and has the right to apply from the schema (Schema Concept). (Conceptual) Schema or Subschema that External or view that this level will see only part of the data structure, such as the case of a relational database view is seen as part of a table. View the data must not duplicate or copy from a table view.
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