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Comment: SUP-346

Constraints are only available in the NIAM view, and they are used for modeling limitations on the relations between entities. There are three types of constraints:

  • Uniqueness constraint for indicating the key of an entity for uniquely identifying the entity. Is linked to attributes of an entity.
  • Exclusion constraint for indicating that each of the entities excludes the other. Is linked to predicates of a fact.
  • Completeness constraint for indicating that two entities together complete the collection. Is linked to predicates of a fact.


On this page:

Table of Contents

Uniquely identifying an entity with uniqueness constraints

Like keys in a Crows Foot logical view, uniqueness constraints can be used for uniquely identifying an entity by linking it to one or more attributes in the entity. A single entity can have multiple uniqueness constraints.

To model the key, add a Uniqueness constraint object to the view. After that connect the key to the attributes in the entity you want to make a part of this key by using a Link relation.

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Setting a sequence number for uniqueness constraints

If multiple uniqueness constraints are used, it is possible to assign them a sequence number. To assign a sequel number, follow these steps:

  1. In the view, select the uniqueness constraint, and then click Image Modified.

    Image Modified

  2. In the Enter sequence number window, type the number and click OK.

The sequence number is now displayed in the constraint:

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Displaying the name of a constraint relation

When a constraint is linked to an attribute in an entity or to a fact, only the constraint is shown with a relation to the other element. To explicitly show which element the constraint is linked to, you can display the name of the relation. To display the name, do as follows:

  • In the view, select the constraint, and then click the name that appears below the constraint.

    Image Modified

The name is now displayed below the constraint:

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You can hide the name again by clicking it.

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