11. Managing Tables and Views : Views
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A view can be thought of as a virtual table. Only the definition for the view is stored, not the data. A table on which a view operates is called a base table.
A view definition can encompass 1 to 380 base tables. It can involve multiple tables joined together by their common columns using a where qualification.
A view can be created on other views or on physical database tables.
A view can be defined on any valid SELECT query that does not contain an ORDER BY, FIRST n, or FETCH FIRST clause.
Note:  Up to 128 table objects (table, view, synonym, and index) can used in a view with the default DBMS Server stack size. To allow the full count of 380 table objects the stack_size needs to be raised to 1.5m (1572864). Failure to do so may result in the session error E_OP08A2.
Primary uses for views include:
Providing security by limiting access to specific columns in selected tables, without compromising database design
Simplifying a commonly used query
Defining reports
UNION ALL views that combine tables of current, recent, and archived data
Because a view is a device designed primarily for selecting data, all selects on views are fully supported. Simply use a view name in place of a table name in the SELECT statement. Updating views is also supported on simple single table views (see Updates on Views), but updating a database by means of a view is not recommended.