Some operations that are permitted on base tables are not permitted on views—sometimes for obvious reasons and sometimes not.
The following set of rules outlines the restrictions on how views can be created and used.
- You cannot create an index on a view.
- A view definition cannot contain an ORDER BY clause.
- Any derived columns in a view must explicitly specify view column names, for example by using an AS clause or by providing a column list immediately after the view name.
- You cannot update tables from a view under the following circumstances:
- The view is defined as a join view (defined on more than one table)
- The view contains derived columns.
- The view definition contains a DISTINCT clause.
- The view definition contains a GROUP BY clause.
- The view defines the same column more than once.