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diff --git a/doc/01-introduction.md b/doc/01-introduction.md index 23184c1..9e61454 100644 --- a/doc/01-introduction.md +++ b/doc/01-introduction.md @@ -102,6 +102,10 @@ Associations between tables are defined through foreign keys. * Referential integrity constraint: each foreign key value must match a primary key value in another relation or the foreign key value must be null. +#### Cardinality + +* Minimum cardinality: The minimum number of instances of one entity that may be associated with each instance of another entity. +* Maximum cardinality: The maximum number of instances of one entity that may be associated with each instance of another entity. ## Well structured relations |