Updating Relational Views

A view is a logical subset of the data base conceptual schema. Providing a facility for supporting views simplifies the user interface, but creates the problem of translating updates on views into equivalent updates on the data base. The translation of a view update may not be unique, it may not even exist or be ill-defined, and it may create inconsistencies in the data base or have side effects on the view. This paper surveys the two basic approaches proposed to solve the view update problem. The first approach suggests treating views as abstract data types so that the definition of a view includes all permissible view updates, together with their translations. The second approach leads to general view update translators and is based either on an analysis of the conceptual schema dependencies or on the concept of view complement to disambiguate view update translations.