Updating oracle views
Oracle materialized views were first introduced in Oracle8, and in Oracle materialized views were enhanced to allow very fast dynamic creation of complex objects.Oracle materialized views allow sub-second response times by pre-computing aggregate information, and Oracle dynamically rewrites SQL queries to reference existing Oracle materialized views.In many cases, the Oracle DBA will encapsulate these grant statements into a single role and grant the role to the end users: Once Oracle materialized views have been enabled, Oracle provides several methods for invoking query rewrite.Query rewrite is generally automatic, but you can explicitly enable it by using Isession, alter system, or SQL hints: In Oracle, if you specify REFRESH FAST for a single-table aggregate Oracle materialized view, you must have created a materialized view log for the underlying table, or the refresh command will fail.The following table shows the DML operations that the Oracle Database adapter supports: Performs an Insert operation on the target table or view.The Insert operation supports multiple record or bulk inserts into the target table or view: - A multiple record Insert operation inserts rows into a table or view based on a supplied record set.In this article, we continue our discussion of Oracle materialized views and discuss how to set up and configure your Oracle database to use this powerful new feature.
The records that the query returns are inserted into the target table based on the column list.
In order to be updatable, a view cannot contain any of the following constructs: SET or DISTINCT operators, an aggregate or analytic function, a GROUP BY, ORDER BY, CONNECT BY, or START WITH clause, a subquery (or collection expression) in a SELECT list or finally (with some exceptions) a JOIN .
In database theory, a view is the result set of a stored query on the data, which the database users can query just as they would in a persistent database collection object.
You can use a view in most places where a table can be used.
All operations performed on a view will affect data in the base table and so are subject to the integrity constraints and triggers of the base table.
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In addition to operating on base tables, one View can be based on another, a view can also JOIN a view with a table (GROUP BY or UNION).