Read-only views: A view is read-only if any of the following appear in its<<<<
- The first FROM clause identifies more than one table or view.
- The first FROM clause identifies a read-only view.
- The first SELECT clause specifies the keyword DISTINCT.
- The outer subselect contains a GROUP BY clause.
- The outer subselect contains a HAVING clause.
- The first SELECT clause contains a column function.
- The subselect contains a subquery such that the base object of the outer
subselect, and of the subquery, is the same table.