Relationships

Posted by AJ × 04:18

A relationship type is a meaningful association between entity types

A relationship is an association of entities where the association includes one entity

from each participating entity type.

Relationship types are represented on the ER diagram by a series of lines.

As always, there are many notations in use today...

In the original Chen notation, the relationship is placed inside a diamond, e.g.

managers manage employees:

For this module, we will use an alternative notation, where the relationship is a label on the line. The meaning is identical

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