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Magazine Problem 2
Discuss insertion, deletion, and modification anomalies. Why are they considered bad? Illustrate with examples.
Problem 3
Why should nulls in a relation be avoided as far as possible? Discuss the problem of spurious tuples and how we may prevent it.
Problem 5
What is a functional dependency? What are the possible sources of the information that defines the functional dependencies that hold among the attributes of a relation schema?
Problem 7
What role do Armstrong's inference rules- -the three inference rules IR 1 through IR3-play in the development of the theory of relational design?
Problem 8
What is meant by the completeness and soundness of Armstrong's inference rules?
Problem 9
What is meant by the closure of a set of functional dependencies? Illustrate with an example.
Problem 11
What is a minimal set of functional dependencies? Does every set of dependencies have a minimal equivalent set? Is it always unique?
Problem 12
What does the term unnormalized relation refer to? How did the normal forms develop historically from first normal form up to Boyce-Codd normal form?
Problem 13
Define first, second, and third normal forms when only primary keys are considered. How do the general definitions of \(2 \mathrm{NF}\) and \(3 \mathrm{NF}\), which consider all keys of a relation, differ from those that consider only primary keys?
Problem 14
What undesirable dependencies are avoided when a relation is in \(2 \mathrm{NF}\) ?
