Views should be created only when they achieve a specific, reasonable goal.
Each view should have a specific application or business requirement that it fulfills before it is created.
Guidelines such as these should be instituted within your organization to reduce the amount of time and effort required to implement effective views.
The following rules will ensure that views are created in a responsible and useful manner at your shop.
For example, the UNION operator can not be used in a view and you cannot create a trigger on a view.