Logical Data Model: A New Approach to Database Logic

摘要

The authors propose a mathematical framework for unifying and generalizing the principal data models, i.e., the relational, hierarchical and network models. The Logical Data Model (LDM) combines the advantages of the relational, network and hierarchical approaches. It models database schemas as directed graphs, in which the leaves correspond to the attributes, and the internal nodes to connections between the data. The authors define a logic on LDM schemas in which integrity constraints can be specified, and use it to define a logical, i.e., non-procedural, query language that is analogous to Codd's relational calculus. The authors also describe an algebraic, i.e., procedural, query language and prove that the two languages are equivalent.