Database Reference
In-Depth Information
3.6.2 One-to-Many (1: M) Relationships
A one-to-many relationship is an association between two entities where any instance of
the first entity may be associated with one or more instances of the second, and any in-
stance of the second entity may be associated with at most one instance of the first.
The relationship between Department and Faculty as shown in the figure, which is mandat-
ory in only one direction, is read as follows: "At any point in time, each Department can
have zero to many Faculties, and each Faculty must have one and only one Department."
One-to-many relationships are quite common. In fact, they are the fundamental building
block of the relational database model in that all relationships in a relational database are
implemented as if they are one-to-many.
