Database Design(Normal Forms)

Question 71

Consider the following three tables R, S and T. In this question, all the join operations are natural joins (⨝). (π) is the projection operation of a relation: (a) (b) (c) (d)

• (a)
• (b)
• (c)
• (d)

Question 72

Purpose of \'Foreign Key\' in a table is to ensure

• Null Integrity
• Referential Integrity
• Domain Integrity
• Null and Domain Integrity

Question 73

Select the \'False\' statement from the following statements about Normal Forms:

• Lossless preserving decomposition into 3NF is always possible
• Lossless preserving decomposition into BCNF is always possible
• Any Relation with two attributes is in BCNF
• BCNF is stronger than 3NF

Question 74

The best normal form of relation scheme R(A, B, C, D) along with the set of functional dependencies F = {AB → C, AB → D, C → A, D → B} is

• Boyce-Codd Normal form
• Third Normal form
• Second Normal form
• First Normal form

Question 75

Which of the following is false?

• Every binary relation is never be in BCNF.
• Every BCNF relation is in 3NF.
• 1 NF, 2 NF, 3 NF and BCNF are based on functional dependencies.
• Multivalued Dependency (MVD) is a special case of Join Dependency (JD).

Question 76

For a database relation R(a,b,c,d) where the domains of a, b, c and d include only atomic values, only the following functional dependencies and those that can be inferred from them hold

a -> c
b -> d

The relation is in

• First normal form but not in second normal form
• Second normal form but not in third normal form
• Third normal form
• None of the above

Question 77

The set of attributes X will be fully functionally dependent on the set of attributes Y if the following conditions are satisfied.

• X is functionally dependent on Y
• X is not functionally dependent on any subset of Y
• Both (a) and (b)
• None of these

Question 78

For a database relation R(a, b, c, d) where the domains of a, b, c and d include only atomic values, and only the following functional dependencies and those that can be inferred from them hold : a → c b → d The relation is in _________.

• First normal form but not in second normal form
• Second normal form but not in third normal form
• Third normal form
• BCNF

Question 79

Consider a relational table R that is in 3NF, but not in BCNF. Which one of the following statements is TRUE ?

• R has a nontrivial functional dependency X→A, where X is not a superkey and A is a prime attribute

• R has a nontrivial functional dependency X→A, where X is not a superkey and A is a non-prime attribute and X is not a proper subset of any key

• R has a nontrivial functional dependency X→A, where X is not a superkey and A is a non-prime attribute and X is a proper subset of some key

• A cell in R holds a set instead of an atomic value

Question 80

Consider the following statements S1 and S2 about the relational data model:

• S1: A relation scheme can have at most one foreign key.
• S2: A foreign key in a relation scheme R cannot be used to refer to tuples of R.

Which one of the following choices is correct?

• Both S1 and S2 are true
• S1 is true and S2 is false
• S1 is false and S2 is true
• Both S1 and S2 are false