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Data Modeling › Extending Relations › Involution and the Horse Pedigrees

Involution and the Horse Pedigrees

One of the purposes of this application is to record details of each horse’s parents (Dam and Sire). To do so you will need to use both the extended form of the Refers to relation and involution.

Since a horse’s parents are also horses, to record the horse’s parents requires two HORSE Refers to HORSE relations, one for each parent. This is shown in the following diagram.

Because the HORSE file refers to itself more than once, you will need to use the extended form of the Refers to relation in order to distinguish between the two relations.