This set of RDBMS Multiple Choice Questions & Answers (MCQs) focuses on “Decomposition Algorithms”.
1. What does the BCNF decomposition algorithm do?
a) States a method to decompose a relation satisfying BCNF
b) States a method for joining two relations satisfying BCNF
c) States a method to decompose a relational schema such that there are no multiple occurrences
d) None of the mentioned
View Answer
Explanation: If a relation is not in BCNF, it can be decomposed into simpler relations that are in BCNF. The BCNF decomposition algorithm states a method to decompose a relation satisfying BCNF.
2. The 3NF decomposition algorithm is also called as _______
a) 3NF normal algorithm
b) 3NF synthesis algorithm
c) 3NF generator
d) Functional dependence algorithm
View Answer
Explanation: The 3NF decomposition algorithm is also called as 3NF synthesis algorithm since it takes a set of dependencies and adds one schema at a time, instead of decomposing the initial schema repeatedly.
3. Which of the following is desirable in a database design with functional dependencies?
a) BCNF
b) Losslessness
c) Dependency preservation
d) All of the mentioned
View Answer
4. State true or false: SQL specifies a way of mentioning functional dependencies
a) True
b) False
View Answer
Explanation: SQL does not specify a way to mention functional dependencies. Functional dependencies are just used for theoretical improvement of database while implementing them in SQL later.
5. State true or false: Most current database systems do not support constraints on materialized view
a) True
b) False
View Answer
Explanation: Most current database systems do not support constraints on materialized view.
6. Multi valued dependencies are also called as __________
a) Equality generating dependencies
b) Tuple generating dependencies
c) Multi-purpose dependencies
d) None of the mentioned
View Answer
Explanation: Multi valued dependencies are also called as tuple generating dependencies because they require other tuples of a certain form to be present in the relation.
7. Functional dependencies are sometimes referred to as ________
a) Equality generating dependencies
b) Tuple generating dependencies
c) Multi-purpose dependencies
d) None of the mentioned
View Answer
Explanation: Functional dependencies are sometimes referred to as equality generating dependencies because they require other tuples of a certain form to be present in the relation.
8. The _______ is a set of all functional and multi values dependencies implied by a set of functional dependencies
a) Star
b) Closure
c) Derivation
d) Evolution
View Answer
Explanation: The closure is a set of all functional and multi values dependencies implied by a set of functional dependencies on a given relation. It is denoted by giving a “+” superscript.
9. State true or false: If a relational schema is in _______ NF and A is a subset of R and B is also a subset of R then it is that A is a superkey is a trivial multi values dependency.
a) 1
b) 2
c) 3
d) 4
View Answer
Explanation: If a relational schema is in 4NF and A is a subset of R and B is also a subset of R then it is that A is a superkey is a trivial multi values dependency.
10. Which of the following normal forms does not exist?
a) BCNF
b) PJNF
c) 5NF
d) None of the mentioned
View Answer
Explanation: All of the mentioned normal forms i.e. BCNF, PJNF, 5NF exist. BCNF is Boyce Codd normal form, 5NF is the fifth normal form and PJNF is project join normal form.
Sanfoundry Global Education & Learning Series – RDBMS.
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