The logical data model

We propose an object-oriented data model that generalizes the relational, hierarchical, and network models. A database scheme in this model is a directed graph, whose leaves represent data and whose internal nodes represent connections among the data. Instances are constructed from objects, which have separate names and values. We define a logic for the model, and describe a nonprocedural query language that is based on the logic. We also describe an algebraic query language and show that it is equivalent to the logical language. © 1993, ACM. All rights reserved.