Normal Forms(Engineering > Computer Science And Engineering > Dbms Questions And Answers ) Questions and Answers
Question 1. Which-one ofthe following statements about normal forms is FALSE?
BCNF is stricter than 3 NF
Lossless, dependency -preserving decomposition into 3 NF is always possible
Loss less, dependency "“ preserving decomposition into BCNF is always possible
Any relation with two attributes is BCNF
View Answer
Explanation:-
Answer: Option A. -> BCNF is stricter than 3 NF
Loss less, dependency “ preserving decomposition into BCNF is always possibleWe say that the decomposition is a lossless decomposition if there is no loss of information by replacing r (R) with two relation schemas r1(R1) andr2(R2).
Question 2. In the __________ normal form, a composite attribute is converted to individual attributes.
First
Second
Third
Fourth
Explanation:-
Answer: Option A. -> First
FirstThe first normal form is used to eliminate the duplicate information.
Question 3. A table on the many side of a one to many or many to many relationship must:
Be in Second Normal Form (2NF)
Be in Third Normal Form (3NF)
Have a single attribute key
Have a composite key
Explanation:-
Answer: Option D. -> Have a composite key
Have a composite keyThe relation in second normal form is also in first normal form and no partial dependencies on any column in primary key.
Question 4. Tables in second normal form (2NF):
Eliminate all hidden dependencies
Eliminate the possibility of a insertion anomalies
Have a composite key
Have all non key fields depend on the whole primary key
Explanation:-
Answer: Option A. -> Eliminate all hidden dependencies
Eliminate all hidden dependenciesThe relation in second normal form is also in first normal form and no partial dependencies on any column in primary key.
Question 5. Functional Dependencies are the types of constraints that are based on______
Key
Key revisited
Superset key
None of these
Explanation:-
Answer: Option A. -> Key
KeyKey is the basic element needed for the constraints.
Question 6. Which is a bottom-up approach to database design that design by examining the relationship between attributes:
Functional dependency
Database modeling
Normalization
Decomposition
Explanation:-
Answer: Option C. -> Normalization
NormalizationNormalisation is the process of removing redundancy and unwanted data.
Question 7. Empdt1(empcode, name, street, city, state,pincode). For any pincode, there is only one city and state. Also, for given street, city and state, there is just one pincode. In normalization terms, empdt1 is a relation in
1 NF only
2 NF and hence also in 1 NF
3NF and hence also in 2NF and 1NF
BCNF and hence also in 3NF, 2NF and 1NF
View Answer
Explanation:-
Answer: Option B. -> 2 NF and hence also in 1 NF
2 NF and hence also in 1 NFThe relation in second normal form is also in first normal form and no partial dependencies on any column in primary key.
Question 8. Which forms simplifies and ensures that there is minimal data aggregates and repetitive groups:
1NF
2NF
3NF
All of the mentioned
Explanation:-
Answer: Option C. -> 3NF
3NFThe first normal form is used to eliminate the duplicate information.
Question 9. Which forms has a relation that possesses data about an individual entity:
2NF
3NF
4NF
5NF
Explanation:-
Answer: Option C. -> 4NF
4NFA Table is in 4NF if and only if, for every one of its non-trivial multivalued dependencies X \twoheadrightarrow Y, X is a superkey”that is, X is either a candidate key or a superset thereof.
Question 10. Which forms are based on the concept of functional dependency:
1NF
2NF
3NF
4NF
Explanation:-
Answer: Option C. -> 3NF
3NFThe table is in 3NF if every non-prime attribute of R is non-transitively dependent (i.e. directly dependent) on every superkey of R.