Relationship types of degree higher than 2 in database.

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Relationship Types of Degree
Higher than Two
Aadesh Shrestha

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Degree of a relationship type
● number of participating entity types ( (binary,
ternary, . . . ))
● a relationship type of degree two - binary
● a relationship type of degree three – ternary
● n-nary

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Binary Relationship
● two entities are involved in binary relationship.
● example "some employees are married to other
employees".

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Ternary Relationship
● three entities are in involved in ternary relationship

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… ternary relationship
● Ternary or n-ary relationships can be decomposed
into two or more binary relationships.

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Constraint on Relationship Types
● Limit the number of possible combinations
of entities thatmay participate in a relationship
set
● Two types of constraint:
– Cardinality ratio
– Participation constraint

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… Cardinality ratio
● cardinality ratio must be one of the following
types

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… Cardinality ratio

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… Cardinality ratio

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… Cardinality ratio

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Participation Constraint
● participation constraint defines the number of times
an object in an object class can participate in a
connected relationship set
● every connection of a relationship set must have a
participation constraint.

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Participation Constraint

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Thank you
Reference Papers
● http://web.cs.ucdavis.edu/~green/courses/ecs165a-w11/2
● http://osm7.cs.byu.edu/OSA/participConst.html
● http://www.webmaster-forums.net/web-programming-and