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DBMS Constraints Multiple-Choice Questions (MCQs)
DBMS Constraints MCQs: This section contains DBMS Constraints Multiple-Choice Questions (MCQs) and Answers.
Submitted by Anushree Goswami, on February 03, 2022
1. Data constraint that expresses how many entities are related through a relationship set is referred to as a ___.
- Data Constraint
- Relationship Constraint
- Entity Constraint
- Mapping Constraint
Answer: D) Mapping Constraint
Explanation:
Data constraint that expresses how many entities are related through a relationship set is referred to as a mapping constraint.
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2. Relationship sets involving ___ are best described using the Mapping Constraint.
- One entity set
- Two entity sets
- More than two entity sets
- Zero entity set
Answer: C) More than two entity sets
Explanation:
Relationship sets involving more than two entities sets are best described using the Mapping Constraint.
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3. How many mapping cardinalities are there?
- 1
- 2
- 3
- 4
Answer: d) 4
Explanation:
There are 4 mapping cardinalities: One to one, Many to one, One to Many, Many to Many.
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4. One to one mapping constraint is denoted as -
- M:1
- 1:M
- M:M
- 1:1
Answer: D) 1:1
Explanation:
One to one mapping constraint is denoted as 1:1.
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5. Many to one mapping constraint is denoted as -
- 1:1
- 1:M
- M:1
- M:M
Answer: C) M:1
Explanation:
Many to one mapping constraint is denoted as 1:M.
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6. A one-to-one mapping relies on at most ____ entity being associated with it.
- One
- Two
- Three
- Many
Answer: A) One
Explanation:
A one-to-one mapping relies on at most one entity being associated with it.
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7. The ___ mapping is a method in which entities in A1 may be associated with any number of entities in A2 and entities in A2 may be associated with any number of entities in A1.
- One to one
- One to many
- Many to one
- Many to many
Answer: B) One to many
Explanation:
The one-to-many mapping is a method in which entities in A1 may be associated with any number of entities in A2 and entities in A2 may be associated with any number of entities in A1.
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8. A ___ mapping assigns a single entity in A1 to at most one entity in A2, and any number of entities in A2 to any number of entities in A1.
- One to one
- One to many
- Many to one
- Many to many
Answer: C) Many to one
Explanation:
A many-to-one mapping assigns a single entity in A1 to at most one entity in A2, and any number of entities in A2 to any number of entities in A1.
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9. The many-to-many mapping involves one entity in A1 being associated with a number of entities in A2, and the reverse is ___.
- False
- Also true
- Boolean
- None
Answer: B) Also true
Explanation:
The many-to-many mapping involves one entity in E1 being associated with a number of entities in E2, and the reverse is also true.
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10. One-to-one mapping constraint is shown by symbol -
- Arrow
- Line
- Pipe
- Square
Answer: A) Arrow
Explanation:
One-to-one mapping constraint is shown by symbol arrow.
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