Whai is Degree of a Relationship Set in Datanase Management System(DBMS)?, What is binary, ternary & n-ary relationship?
Definition
Degree of Relationship Set refers to number of entity sets that participate in a relationship
set.
1) Relationship sets that involve two entity sets are binary (or degree two). Generally, most relationship sets in a database system are binary.
2) Relationship sets may involve more than two entity sets.
E.g. Suppose employees of a bank may have jobs
(responsibilities) at multiple branches, with different jobs at
different branches. Then there is a ternary relationship set
between entity sets employee, job and branch
3) Relationships between more than two entity sets are rare. Most
relationships are binary.
Binary Vs. Non-Binary Relationships
Some relationships that appear to be non-binary may be better
represented using binary relationships
E.g. A ternary relationship parents, relating a child to his/her father and
mother, is best replaced by two binary relationships, father and mother
Using two binary relationships allows partial information (e.g. only
mother being know)
But there are some relationships that are naturally non-binary
E.g. works-on
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