AN ANALYSIS OF SQL INTEGRITY CONSTRAINTS FROM AN ENTITY-RELATIONSHIP MODEL PERSPECTIVE

Citation
Ahf. Laender et al., AN ANALYSIS OF SQL INTEGRITY CONSTRAINTS FROM AN ENTITY-RELATIONSHIP MODEL PERSPECTIVE, Information systems, 19(4), 1994, pp. 331-358
Citations number
23
Categorie Soggetti
System Science","Information Science & Library Science","Computer Science Information Systems
Journal title
ISSN journal
03064379
Volume
19
Issue
4
Year of publication
1994
Pages
331 - 358
Database
ISI
SICI code
0306-4379(1994)19:4<331:AAOSIC>2.0.ZU;2-9
Abstract
This paper presents an analysis of the integrity constraints defined i n the SQL ISO standard disclosure in the light of the entity-relations hip model. It points out what features of integrity constraints in SQL support which features of the entity-relationship model by discussing how to map an entity-relationship schema into a SQL schema. In order to organize the analysis, the paper distinguishes three levels of the entity-relationship model. The first level corresponds to the basic mo del, augmented with simple specializations. The second level considers totality and more complex specializations, and allows deferred and im mediate propagation of deletions. Finally, the third level introduces generalization hierarchies and considers some types of inter-relations hip constraints. For the first and second levels, the analysis indicat es that the more complex features of the SQL referential integrity con struct are necessary only when optimization is considered, but one of the features - propagation of nulls - should be slightly enhanced to e asy the optimization task. However, for the third level, the analysis shows that, in most cases, the SQL referential integrity construct can efficiently model subsetting, but that the direct use of SQL integrit y constraints to account for mutual exclusion may be very expensive.