These constraints arise frequently.
Every relation arising from a relationship set has referential integrity
constraints.
Figure 6.1: An n-ary relationship set
- Figure 6.1 shows an n-ary relationship set R
relating entity sets .
- Let denote the primary key of .
- The attributes of the relation scheme for relationship set R
include .
- Each in the scheme for R is a foreign key that leads
to a referential integrity constraint.