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Glossary of relationship terms

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There are a number of terms used to describe relationships. It is not necessary to understand all these terms up-front. Refer back here as needed when reading the relationships documentation pages.

  • Dependent entity: This is the entity that contains the foreign key property or properties. A dependent is sometimes called a "child".
  • Principal entity: This is the entity that contains the primary/alternate key property or properties. A principal is sometimes called the "parent".
  • Principal key: The property or properties whose values uniquely identify the principal entity. The principal key may be the primary key or an alternate key.
  • Foreign key: The property or properties of the dependent entity type that are used to store the key values that match the principal key values of the related principal entity.
  • Navigation: A property on the entity on one side of the relationship that references the related entity or entities at the other end of the relationship.
    • Collection navigation: A navigation that contains references to many related entities. Used to reference the "many" side(s) of one-to-many and many-to-many relationships.
    • Reference navigation: A navigation that holds a reference to a single related entity. Used to reference the "one" side(s) of one-to-one and one-to-many relationships.
    • Inverse navigation: When discussing a particular navigation, this term refers to the navigation on the other end of the relationship.
  • Self-referencing relationship: A relationship in which the dependent and the principal entity types are the same.
  • Required relationship A relationship represented by a non-nullable foreign key. A dependent entity in a required relationship cannot exist without a principal entity to which it refers.
  • Optional relationship A relationship represented by a nullable foreign key. A dependent entity in an optional relationship can exist without referring to any principal entity.
  • Bidirectional relationship A relationship that has navigations on both sides of the relationship.
  • Unidirectional relationship A relationship that has a navigation on one side of the relationship, but no navigation on the other side.