Cardinality


 * Dutch: Kardinaliteit
 * See also: Crow's Foot Notation

Introduction

 * In an entity-relationship model you can visualise the cardinality between two entities using Crow's Foot notation.
 * In the example below you see an optional relationship between Artist and Song.
 * The symbols closest to the song entity represents "zero, one, or many", whereas a song has "one and only one" Artist.
 * The former is therefore read as, an Artist (can) perform(s) "zero, one, or many" song(s).