Cardinality :: Tip o' The Day

A quick tip o’ the day.  I also posted this answer on WikiAnswers for the question, “What is the cardinality of a data type eg integer?

“Cardinality is the total number of unique occurrences of an entity (e.g. person, organization, or transaction) that can be included in a relationship.

A URI/URL, e-mail, phone number should be unique, providing a high cardinality. This means that each of the entity values would be represented at least once in a relationship.

A lower cardinality value would be something like a bit, or boolean value. This value will only occur twice before becoming redundant in a relationship.”

Also find a great definition and relationship description at datamodel.org for cardinality and at WikiPedia of course there is an entry on the cardinality subject.