An entity-relationship algebra and its semantic description capabilities

doi:10.1016/0164-1212(84)90005-0

Journal of Systems and Software

Volume 4, Issues 2–3, July 1984, Pages 147-162

https://doi.org/10.1016/0164-1212(84)90005-0 Get rights and content

Abstract

The entity-relationship model (ERM) has been defined without a manipulative part. Since a link between the ERM and the relational model may be established by choosing the relation to be the structural unit of the data-representational level of the ERM, this model could benefit by somehow inheriting the relational algebra. This paper proposes as manipulative part for the entity-relationship model a reshaped relational algebra (RRA). It is shown that just as the entity-relationship model concepts are based on the way people perceive information, the RRA operators bear analogies to the way people communicate, i.e., natural language, and are therefore convenient in describing the semantics of query languages within ERM.

References (14)

A.L. Furtado
Formal aspects of the relational model
P. Atzeni et al.
Completeness of query languages for the entity-relationship model
P.P. Chen
The Entity-Relationship Model Toward a Unified View of Data
ACM Trans. Database Syst.
(March 1976)
E.F. Codd
Relational completeness of database sublanguages
E.F. Codd
Relational Databases: A Practical Foundation for Productivity
Commun. ACM
(Feb 1982)
P. Hall et al.
Relations and entities
W. Kent
Data and Reality
(1978)

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Query abbreviation in the Entity-Relationship data model
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This paper examines the idea of context inference, which is the ability of a query processor to infer the appropriate relationships between the classes mentioned in a query. Context inference has been the basis of Universal Instance (UI) data models. We show that context inference can be applied to the Entity-Relationship model, resulting in a compact, high-level language without the undesirable restrictions associated with UI databases. We also show how the traditional notions of inheritance and path expressions can be considered to be special cases of context inference.
Roles and their role in posing recursive queries
1990, Information Systems
We show how to use the entity-relationship diagram as a vehicle for specifying the semantics of attributes. A main contribution of this work is a strategy for creating entity-relationship diagrams that make explicit the role of attributes that are over the same domain. Recursive queries can be posed over the universal relation when attributes are over the same domain and play distinct roles. We show how to extend a query language, that poses queries over the universal relation, to include the ability to express recursive queries.
An extended ER algebra to support semantically richer queries in ERDBMS
2015, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
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An entity-relationship algebra and its semantic description capabilities

Abstract

Completeness of query languages for the entity-relationship model

The Entity-Relationship Model Toward a Unified View of Data

ACM Trans. Database Syst.

Relational completeness of database sublanguages

Relational Databases: A Practical Foundation for Productivity

Commun. ACM

Relations and entities

Data and Reality