The UR data model revisited

The universal relation (UR) model is an attempt to achieve a very simple user interface by allowing the formulation of queries with respect to a single, imaginary relation (i.e., universal relation) defined over all the attributes appearing in the various relations of a database, while producing answers from the actual relations of the database. Previous publications covering the universal relation model have been too technical to be easily understood, and have not offered a solution to the ambiguity problem for which the universal relation model has achieved much criticism. This paper provides an accessible introduction to the universal relation model, which helps to clarify the misunderstanding of the universal relation model. It also provides a confirmation approach to solve the ambiguity problem, facilitating successful application of the model.