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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 ___.

1. Data Constraint
2. Relationship Constraint
3. Entity Constraint
4. 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.

1. One entity set
2. Two entity sets
3. More than two entity sets
4. 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. 1
2. 2
3. 3
4. 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 -

1. M:1
2. 1:M
3. M:M
4. 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
2. 1:M
3. M:1
4. 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.

1. One
2. Two
3. Three
4. 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.

1. One to one
2. One to many
3. Many to one
4. 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.

1. One to one
2. One to many
3. Many to one
4. 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 ___.

1. False
2. Also true
3. Boolean
4. 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 -

1. Arrow
2. Line
3. Pipe
4. Square

Answer: A) Arrow

Explanation:

One-to-one mapping constraint is shown by symbol arrow.

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