Relations and Entities . In G. M. Nijssen, editor, Modelling in Data Base Management Systems, pp. We also assume that a domain of surrogates is included among these domains. Relations and Entities . A description of the time domains is given shortly.
Surrogates are system generated unique internal identifiers.
Relations and Entities . It allows to distinguish objects even if they coincide in their values. Here, internal means that the query language of a data model does not provide direct access to the identifiers. P. Hall, J. Owlett, and S. Todd. Relations and entities .