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.
- Database System
- Member Relation
- Single Relation
- Virtual Attribute
- Semantical Richness
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