Views present significant problems if updates are expressed with them. The difficulty is that a modification to the database expressed in terms of a view MUST be translated to a modification to the actual relations in the logical model of the database.

1. Since the view may not have all the ATTRIBUTES of the underlying tables, insertion of a tuple into the view will INSERT tuples into the underlying tables, with those attributes not participating in the view getting null values. This may not be desirable, especially if the attribute in question is part of the primary key of the table.
2. If a view is a join of several underlying tables and an insertion results in tuples with nulls in the join columns, the desired effect of the insertion will not be ACHIEVED. In other words, an update to a view may not be expressible at all as updates to base relations.

Views present significant problems if updates are expressed with them. The difficulty is that a modification to the database expressed in terms of a view must be translated to a modification to the actual relations in the logical model of the database.