Cardinality of a RelationshipRelationship cardinality specify how many of each entity type is allowed. Relationships can have four possible connectivities as given below. One to one (1:1) relationship One to many (1:N) relationship Many to one (M:1) relationship Many to many (M:N) relationshipTaken from http://www.softwaredevelopersworld.com/db/rdbms/c1/design.php
Point to be noted here,Relation and Relationship are different!!!