ER modelling

Question 1

Relationship Cardinalities/multiplicities

Answer 1

Used to restrict how entity types participate in relationships in order to model real-world

Question 2

Multiplicity

Answer 2

Number of possible occurrences of an entity type that may relate to a single occurrence of an associated entity type through a particular relationship

Question 3

Participation constraint

Answer 3

Determines if every member in a superclass must participate as a member of one of its subclasses. (optional/mandatory)

Question 4

Disjoint constraint

Answer 4

Determines if a member of a superclass can be a member of one or more than one of it subclasses(OR/AND)