model - toward a unified view of data.
26) Robert Maxwell has provided a much more detailed discussion, which treats diagramming methods for entity-relationship
models, comparing Chen's system and those used in FRBR and FRAD, and then moves to a consideration of the FRBR entities, relationships, and user tasks, ending with a comparison between the FRBR model and catalogue records produced under AACR2.
Let us briefly review the key definitions of Entity-Relationship
schemata following .
model--toward a unified view of data.
modeling, which "divides a given data universe (e.
A semantic database designer would always produce an entity-relationship
diagram like that shown in Figure 2 before he or she would proceed with the table design options of Figure 1.
Figure 1 illustrates an Entity-Relationship
diagram that expresses a relationship (prefers) between two entities: customer and product.
Questions of file design, record construct, and entity-relationship
definition were critical to the advancement of the catalog as a tool of the modern age.
Codd also objects to the entity-relationship
model on the grounds that it does not allow associations to have properties.
Green, who did most of the original coding, with the support of the Michigan Consortium for Family Practice Research, CLINFOTRACKER is described as "a straightforward information systems platform--an entity-relationship
As an example of a solution, the next section investigates a method to organize and model geographic objects using the analysis of entity-relationship
and the relational database models.
(ER) model, originally proposed by Chen , has been used widely for conceptual design Lenzerini and Nobili .