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Unary Relationships (recursive)

19 January, 2016 - 14:28

One in which a relationship exists between occurrences of the same entity set

The two keys (primary key and foreign key) are the same but they represents two entities of different roles relate to this relationship.

In some entities, a separate column can be created that refers to the primary key of the same entity set.

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Figure 8.8 Source: http://cnx.org/content/m28250/latest/