2.40 What is the multivalue, multicolumn problem? What is a multivalued dependen
ID: 3745749 • Letter: 2
Question
2.40 What is the multivalue, multicolumn problem? What is a multivalued dependency, and how is it resolved by 4NF? To answer these questions, consider the following relation: STUDENT(StudentNumber, StudentName, SiblingName, Major) Assume that the values of SiblingName are the names of all of a given student’s brothers and sisters; also assume that students have at most one major. .
A.Define and discuss the multivalue, multicolumn problem. Define and discuss a multivalued dependency.
B. Show an example of this relation for two students, one of whom has three siblings and the other of whom has only two siblings.
C. List the candidate keys in this relation.
D. State the functional dependencies in this relation.
E. Explain why this relation does not meet the relational design criteria set out in this chapter (that is, why this is not a well-formed relation).
F. Define and discuss 4NF and how 4NF can be used to allow a set of well-formed relations.
G. Divide this relation into a set of relations that meet the relational design criteria (that is, that are well formed). Specify the type of final normal form for each the final relations.
Explanation / Answer
The multivalue, multicolumn problem occurs when the table contains multiple values of a particular type of attribute. As in the above example, for column sibling name, there can be multiple names in this column for in a particular student.
Multivalued dependencies is a condition among tuples of a relation when the relation is showcasing multiple manymany relationship. In 4NF , MVD’s are treated as FD’s during decomposition, but not while determining the keys os a relation.
Eg
C. Candidate keys are student number or combination of student number+student name
D. Student Number-> Student name
Student Number -> Major
Student Number, Student name -> Major
Number NAme Sibling Major 1 abc abc1 M1 1 abc abc2 M1 1 abc abc3 M1 2 xyz xyz1 M2 2 xyz xyz2 M2Related Questions
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