Different views of a data base

The problem of data base access via different data models has been investigated for the network model and the relational model. The network model is based on the Codasyl proposal (1), which has been modified in two major respects: only one member record type is allowed per set type, and one data item of each record type is assumed to serve as primary key. For a given network model of the data base a coexistent relational model is proposed. The proposal is based on an extension of the usual relational model (2) by an incorporation of appropriate network parameters.