Engineering Questions with Answers - Multiple Choice Questions

# Oracle Database MCQs

1 - Question

1. A table is in BCNF if it is in 3NF and if every determinant is a ___________ key.
a) Dependent
b) Normal
c) Candidate
d) Both Normal and Candidate

Explanation: A table is in Boyce-Codd normal form (BCNF) if and only if it is in 3NF and every determinant is a candidate key.

2 - Question

2. The ___________ normalization introduced by Chris Date, Hugh Darwen, and Nikos Lorentzos.
a) Third
b) Fourth
c) Fifth
d) Sixth

Explanation: Chris Date, Hugh Darwen, and Nikos Lorentzos introduced Sixth Normal form (6NF).

3 - Question

3. A table is in 3NF if it is in 2NF and if it has no ____________
a) Functional Dependencies
b) Transitive Dependencies
c) Trivial Functional Dependency
d) Multivalued Dependencies

Explanation: For a relation to be in Third Normal Form, it must be in Second Normal form and the following must satisfy:No non-prime attribute is transitively dependent on prime key attribute For any non-trivial functional dependency, X -> A, then eitherX is a superkey or,A is prime attribute.

4 - Question

4. Every constraint on the table is a logical consequence of the table’s
a) Fourth normal form
b) Fifth normal form
c) Domain/key normal form
d) None of the Mentioned

Explanation: A relation is in domain-key normal form (DK/NF) if every constraint on the relation is a logical consequence of the definition of keys and domains.

5 - Question

5. A ___________ is an indirect functional dependency, one in which X->Z only by virtue of X->Y and Y->Z.
a) Multivalued Dependencies
b) Join Dependency
c) Trivial Functional Dependency
d) Transitive Dependencies

Explanation: Third Normal Form deals with something called ‘transitive’ dependencies. This means if we have a primary key A and a non-key domain B and C where C is more dependent on B than A and B is directly dependent on A, then C can be considered transitively dependent on A.

6 - Question

6. In a given relationship R, if an attribute A uniquely defines all other attributes, then the attribute A is a key attribute which is also known as the _________ key.
a) Candidate
b) Join
c) Functional
d) None of the Mentioned

Explanation: A candidate key is a column, or set of columns, in a table that can uniquely identify any database record without referring to any other data. Each table may have one or more candidate keys.

7 - Question

7. Anomalies are avoided by splitting the offending relation into multiple relations, is also known as
a) Accupressure
b) Decomposition
c) Precomposition
d) Both Decomposition and Precomposition

Explanation: Eliminate redundancy by decomposing a relation into several relations in a higher normal form.

8 - Question

8. Every time attribute A appears, it is matched with the same value of attribute B, but not the same value of attribute C. Therefore, it is true that:
a) A -> B
b) A -> C
c) A -> (B,C)
d) (B,C) -> A

Explanation: Transitivity rule: Same as transitive rule in algebra, if a -> b holds and b -> c holds then a -> c also hold. a -> b is called as a functionally determines b.

9 - Question

9. When the values in one or more attributes being used as a foreign key must exist in another set of one or more attributes in another table, we have created a(n):
a) Transitive Dependency
b) Insertion Anomaly
c) Referential Integrity Constraint
d) Normal Form

Explanation: Referential Integrity is set of constraints applied to foreign key which prevents entering a row in child table for which you don’t have any corresponding row in parent table i.e. entering NULL or invalid foreign keys.

10 - Question

10. Which of the following is not a restriction for a table to be a relation?
a) The cells of the table must contain a single value
b) All of the entries in any column must be of the same kind
c) The columns must be ordered
d) No two rows in a table may be identical