Compatible attributes in a universal relation

摘要

The problem of entities that play multiple roles in a relational database is studied, with an emphasis on the universal relation view of the database. A tree structure is used to describe the compatibilities among attributes. The compatibility information for an attribute encodes role playing information that cannot be described by traditional data dependencies. This structure is used to define the semantics of a QUEL-like (Stonebraker et al. [1976]) query language that uses special naming rules to permit easy use of attribute compatibility