Usage:

CREATE TRIGGER ON name INSTEAD OF INSERT|UPDATE|DELETE AS FOR EACH ROW block

Syntax Rules:

• The target, name, must be an updatable view.

• An INSTEAD OF TRIGGER must not yet exist for the given event.

• Triggers are not yet true schema objects. They are scoped only to their view and have no name.
  Limitations:

• There is no corresponding drop operation. See Alter Trigger for enabling/disabling an existing trigger.