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Domain Constraints
Domain constraints are primarily formed for defining the logically correct values for an attribute of a relation. The relation allows attributes of a relation to be confined to a range of values, for instance, values of an attribute age can be restricted as Zero to 150 or a definite type like integers, etc.
REDUNDANCY AND ASSOCIATED PROBLEMS
Let us take the subsequent relation STUDENT
Enrolment no
Sname
Address
Cno
Cname
Instructor
Office
050112345
Rahul
D-27, main Road
Ranchi
MCS-011
Problem
Solution
Nayan
Kumar
102
D-27, Main Road
MCS-012
Computer
Organisation
Anurag
Sharma
105
MCS-014
SSAD
Preeti
Anand
103
050111341
Aparna
B-III, Gurgaon
Figure: A state of STUDENT relation
The above relation satisfies the properties of a relation and is said to be in first normal form (or 1NF). Theoretically it is convenient to have all the information in one relation as it is then likely to be simpler to query the database. But the relation over has the following undesirable kinds:
What are domain constraints? A domain is a set of values that might be assigned to an attribute .all values that appear in a column of a relation must be taken from the similar
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