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Specified on each participation
of an entity type E in a relationship type R
Specifies that each entity e in E
participates in at least min and at most max
relationship instances in R
Default(no constraint): min=0,
max=n (signifying no limit)
Must have min_max, min_0, max _1
Derived from the knowledge of
mini-world constraints
Examples:
A department has exactly one
manager and an employee can manage at most one
department.
Specify (0,1) for participation
of EMPLOYEE in MANAGES
Specify (1,1) for participation
of DEPARTMENT in MANAGES
An employee can work for exactly
one department but a department can have any
number of employees.
Specify (1,1) for participation
of EMPLOYEE in WORKS_FOR
Specify (0,n) for participation of DEPARTMENT in
WORKS_FOR
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