Inclusion Dependencies

Abstract

Inclusion dependencies support an essential semantics of the standard relational data model. An inclusion dependency is defined as the existence of attributes (the left term) in a table R whose values must be a subset of the values of the corresponding attributes (the right term) in another table S (Abiteboul, Hull & Vianu, 1995; Codd, 1990; Connolly, Begg & Strachan, 1999; Date, 2000). When the right term conforms a unique column or a primary key (K) for the table S, the inclusion dependency is key-based (also named referential integrity restriction, rir). In this case, the left term is a foreign key (FK) in R and the restriction is stated as R[FK] <