A theory of reference graphs in relational databases
An attempt is made to enhance the data modelling capabilities of the relational model. Reference pairs and reference graphs of relations are introduced as larger meaningful units than single relations are.
A reference pair models a stylized form of a referential integrity constraint. Together, the reference pairs in a database form a directed graph, which we call a reference graph. Reference graphs add to the relational model a structuring mechanism that is more general than and yet as elegant as related constructs such as complex objects, non first normal form or nested relations.
On these reference graphs an algebra is defined. For single node reference graphs this algebra is reduced to the classical relational algebra. The semantical richness of reference graphs is demonstrated by studying some possible effects on the SQL query language.
KeywordsDatabase System Member Relation Single Relation Virtual Attribute Semantical Richness
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- BERN76.P.A. Bernstein. "Synthesizing third normal form relations from functional dependencies." In Transactions on Database Systems 1, 4 (Dec. 1976), pp. 277–298.Google Scholar
- CODD79.E.F. Codd. "Extending the relational model to capture more meaning." In Transactions on Database Systems 4, 4 (Dec. 1979), pp. 397–434.Google Scholar
- DATE81.C.J. Date. "Referential integrity." in Proc. Conf. Very Large Databases, Cannes, 9–11 Sept. 1981, pp. 2–11.Google Scholar
- HASK82.R.L. Haskin and R.A. Lorie. "On extending the functions of a relational database system." In Proc. SIGMOD Intl. Conf. on Management of Data, Orlando, June 1982, pp. 207–212.Google Scholar
- JAES82.G. Jaeschke and H.-J. Schek. "Remarks on the algebra of non first normal form relations." In Proc. of ACM SIGACT-SIGMOD Symposium on Principles of Database Systems, Los Angeles, March 1982.Google Scholar
- KORT80.H.F. Korth and J.D. Ullman. "System/U: a database system based on the universal relation assumption." In Proc. XP/1 Conf., 1980.Google Scholar
- LIEN81.E.Y. Lien. "Hierarchical schemata for relational databases." In Transactions on Database Systems 6, 1 (March 1981), pp. 48–69.Google Scholar
- LORI83.R. Lorie and W. Plouffe. "Complex objects and their use in design transactions." In Proc. of Annual IEEE Meeting — Database Week, 1983.Google Scholar
- MAIE84.D. Maier, J.D. Ullman, M.Y. Vardi. "On the foundations of the universal relation model." In Transactions of Database Systems 9, 2 (June 1984), pp. 283–308.Google Scholar
- MAKI77.A. Makinouchi. "A consideration on normal form of not-necessarily-normalized relations in the relational data model." In Proc. Conf. Very Large Databases, Tokyo, 1977, pp. 447–435.Google Scholar
- SCHE82.H.-J. Scheck and P. Pistor. "Data structures for an integrated data base management and information retrieval system." In Proc. Conf. Very Large Databases, Mexico City, Sept. 8–10 1982, pp. 197–207.Google Scholar
- SMIT77.J.M. Smith and D.C.P. Smith. "Database abstractions: aggregation and generalization." In Transactions on Database Systems 2, 2 (July 1977), 105–133.Google Scholar
- ULLM82.J.D. Ullman. Principles of database systems, 2nd edition. Computer Science Press, Rockville, Maryland (1982), 484 p.Google Scholar