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DBMS Relational Decomposition MCQs: This section contains multiple-choice questions and answers on relational decomposition in DBMS.
Submitted by Anushree Goswami, on April 04, 2022
1. In the ___, the decomposition of a relationship is necessary if a relationship is in an inappropriate normal form.
- Rational Model
- Relational Model
- Reasonable Model
- Rectifiable Model
Answer: B) Relational Model
Explanation:
In the relational model, the decomposition of a relationship is necessary if a relationship is in an inappropriate normal form.
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2. The relational decomposition of a database divides the table into ___ tables.
- New
- Two
- Three
- Multiple
Answer: D) Multiple
Explanation:
The relational decomposition of a database divides the table into multiple tables.
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3. There may be problems such as loss of information if the relation lacks ___.
- Proper Decomposition
- Improper Decomposition
- Both A and B
- None of the above
Answer: A) Proper Decomposition
Explanation:
There may be problems such as loss of information if the relation lacks proper decomposition.
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4. By decomposing the design, ___ associated with bad design are reduced.
- Anomalies
- Inconsistencies
- Redundancies
- All of the above
Answer: D) All of the above
Explanation:
By decomposing the design, anomalies, inconsistencies, and redundancies associated with bad design are reduced.
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5. How many types of decomposition are there?
- 1
- 2
- 3
- 4
Answer: B) 2
Explanation:
There are two types of decomposition : Lossy Decomposition and Lossless Join Decomposition.
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6. Which of the following is a type of decomposition?
- Lossless Decomposition
- Dependency Preserving
- Both A and B
- None of the above
Answer: C) Both A and B
Explanation:
The types of decompositions are -
- Lossless Decomposition
- Dependency Preserving
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7. ___ decomposition takes place if information from the relation to be decomposed is not lost.
- Lossless
- Loss
- Dependency
- Independency
Answer: A) Lossless
Explanation:
Lossless decomposition takes place if information from the relation to be decomposed is not lost.
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8. Decomposition by lossless means guarantees that joining relations will produce the ____ relation as when they were decomposed.
- Different
- Same
- Two
- Multiple
Answer: B) Same
Explanation:
Decomposition by lossless means guarantees that joining relations will produce the same relation as when they were decomposed.
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9. If there are ___ between all the decompositions, the relation is said to be lossless decomposition.
- Inner Joins
- Outer Joins
- Full Outer Joins
- Natural Joins
Answer: D) Natural Joins
Explanation:
If there are natural joins between all the decompositions, the relation is said to be lossless decomposition.
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10. Databases are obligated to ___ dependencies.
- Not preserve
- Preserve
- Spread
- Not Spread
Answer: B) Preserve
Explanation:
Databases are obligated to preserve dependencies.
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11. In dependency preservation, every dependency must be satisfied by at least ___ decomposed table.
- Four
- Three
- Two
- One
Answer: D) One
Explanation:
In dependency preservation, every dependency must be satisfied by at least one decomposed table.
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12. ___ a relation R into its dependency relations R1 and R2 requires that the dependencies of R either be a part of R1 or R2 or be derivable from the combination of the functional dependency relationships of R1 and R2.
- Composing
- Decomposing
- Both A and B
- None of the above
Answer: B) Decomposing
Explanation:
Decomposing a relation R into its dependency relations R1 and R2 requires that the dependencies of R either be a part of R1 or R2 or be derivable from the combination of the functional dependency relationships of R1 and R2.
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