which returns a literal of type set. In this example, we have used the DEFINE
statement to create a view in OQL and then queried this view to obtain the required
result. In OQL, the name of the view must be a unique name among all named objects,
classes, methods, or function names in the schema. If the name specified in the DEFINE
statement is the same as an existing schema object, the new definition replaces the previous
one. OQL also allows a view to have parameters, so we can generalize the above
view as: