Use the SCHEMABINDING option to prevent changes to base objects. Similarly, if a column was dropped from the base table, invoking the view results in an error. For example, a view that uses SELECT * doesn’t display columns that were added later to the base table. View definitions are evaluated when they are created and aren’t affected by subsequent changes to the underlying tables. For more information, see Overview of SQL Server Security. You can perform permission management at the view level without explicit permissions to the base objects, provided the ownership chain is maintained. You can use this approach to provide backward compatible views of data.Īs a security mechanism, a view can screen and filter source table data.
Create view psql code#
You can change the underlying tables without the need to modify the application code as long as the expected results of the view don’t change.
You can use distributed views to query other databases and data sources using linked servers.Īs an abstraction layer, a view can decouple application code from the database schema. They can JOIN and UNION data from multiple source tables and use aggregates, window functions, and other SQL features as long as the result is a semi-proper set with uniquely identifiable columns and no order to the rows. Views are used as abstraction layers and security filters for the underlying tables. They consist only of a query definition and are reevaluated for each invocation. With the exception of indexed views, view objects don’t store data. Similar to tables, views are data sets with uniquely named columns and rows. Views are schema objects that provide stored definitions for virtual tables. PostgreSQL doesn’t support indexed and partitioned views.
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