engleză
Despite the considerable activity in the area of temporal databases, no temporal database model has achieved the same level of acceptance as Codd s relational model in the world of conventional databases. Existing temporal database models differ significantly in the way they incorporate temporal components as well as in the algebras they define. The research reported in this book combines the features of previous nested and temporal models to develop a new integrated Temporal Nested Model (TNM), an attribute timestamping heterogeneous model supporting temporal elements as distinct temporal attributes. Operations can be performed recursively at any level of TNM relations and are formally defined and proved to be closed. TNM is defined as a superset of the Nested Relational Model (NRM) also defined in this book. The major contributions of NRM are the formal definitions of the rename and natural join operations. The latter is extended to support the temporal dimension in the TNM. The book is especially useful to professionals actively involved in temporal database research or anyone else who may be considering utilising nested relations in databases.
