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Mastering Data Modeling: A User-Driven Approach by John Carlis

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Chapter 12. Shapes with Reflexive Relationships

A reflexive relationship is a relationship connecting an entity to itself. A reflexive relationship can be one-one, one-many, or many-many.

Shape: One-One Reflexive Relationship

A reflexive relationship can be a one-one relationship. For example, LDS Fragment 12-1 indicates the following:

  • Each student can tutor one student.

  • Each student can be tutored by one student.

Image

Fragment 12-1

Whenever you see a reflexive one-one relationship on an LDS, your first instinct should be to see if it is missing a chicken foot. In most cases, the users will indicate that the reflexive one-one relationship ...

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