Cardinality expresses the minimum and maximum number of instances of an
entity B that can be associated with an instance of an entity A. The
minimum and the maximum number of instances can be equal to 0, 1, or N.
Cardinalities indicate whether the relationship or join between two tables is one-to-many (1,N), one-to-one (1,1), or many-to-many (N, N). Because a join is bi-directional, it must always have two cardinalities.
Cardinalities indicate whether the relationship or join between two tables is one-to-many (1,N), one-to-one (1,1), or many-to-many (N, N). Because a join is bi-directional, it must always have two cardinalities.
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