A view provides an alternative way of looking at the data in one or more tables.
A view is a named specification of a result table. The specification is a SELECT statement that is effectively executed whenever the view is referenced in an SQL statement. Thus, a view can be thought of as having columns and rows just like a base table. For retrieval, all views can be used just like base tables. Whether a view can be used in an insert, update, or delete operation depends on its definition.
An index cannot be created for a view. However, an index created for a table on which a view is based may improve the performance of operations on the view.
When the column of a view is directly derived from a column of a base table, that column inherits any constraints that apply to the column of the base table. For example, if a view includes a foreign key of its base table, INSERT and UPDATE operations using that view are subject to the same referential constraints as the base table. Likewise, if the base table of a view is a parent table, DELETE operations using that view are subject to the same rules as DELETE operations on the base table. A view also inherits any triggers that apply to its base table. For example, if the base table of a view has an update trigger, the trigger is fired when an update is performed on the view.
A view has a name and may have a different system name. The system name is the name used by i5/OS. Either name is acceptable wherever a view-name is specified in SQL statements.
A column of a view has a name and may have a different system column name. The system column name is the name used by i5/OS. Either name is acceptable wherever column-name is specified in SQL statements.
A view is created with the CREATE VIEW statement. For more information about creating views, see CREATE VIEW.