## NPTEL Introduction to Database Systems Week 2 Assignment Answers 2024

1. An attribute of an entity can be both simple as well as multi-valued

- True
- False

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2. Only entity sets/types can have attributes associated with them.

- True
- False

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3. An attribute of an entity can be both composite as well as single-valued.

- True
- False

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4. An attribute of an entity can be both composite as well as simple.

- True
- False

Answer :-

5. Consider the statements:

S1: The key of an entity type always consists of a single attribute.

S2: The key of an entity type may have more than one attribute.

S3: An entity type has exactly one key.

S4: An entity type may have more than one key.

Which of the following is correct?

- S1 and S3 are TRUE
- S1 and S4 are TRUE
- S2 and S3 are TRUE
- S2 and S4 are TRUE

Answer :-

6. Suppose X is a composite attribute of an entity type and has three components – C1, C2 and C3, where only C2 is multi-valued. If domain

sets of C1, C2 and C3 have 5, 3, and 4 elements respectively, what is the size of the domain of X?

- 60
- 12
- 120
- 160

Answer :-

7. Suppose R is a relationship type with three participating entity types E1, E2, E3. If the number of entities in E1, E2 and E3 are 5, 10,

and 4, respectively, the cardinality of the set of *all possible *instances of R is:

- 19
- 200
- 2
^{200} - 3
^{200}

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8. suppose ** isPartOf **is a relationship type with two participating entity types

** and**

*District***. What is the appropriate cardinality ratio**

*State*for District:State?

- 1:N
- N:1
- M:N
- 1:1

Answer :-

9. Suppose * Author* is a relationship type with two participating entity types

** and **

*Person***. What is the appropriate cardinality ratio for Person:Book?**

*Book*- 1:N
- N:1
- M:N
- 1:1

Answer :-

10. Consider the binary relationship type ** BiologicalMother** between entity types

**and**

*Person*** . Suppose the cardinality ratio**

*Woman*(Person: Woman) constraint of the relationship is expressed using (min,max) notation as (u,v) on the line connecting Person

to BiologicalMother and (x,y) on the line connecting Woman to BiologicalMother, which one of the following is correct:

- (u,v) = (1,1); (x,y) = (1,N)
- (u,v) = (1,N); (x,y) = (1,N)
- (u,v) = (1,1); (x,y) = (0,N)
- (u,v) = (1,N); (x,y) = (0,N)

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11. Suppose entity set A = {a,b,c,d,e} and entity set B = {w,x,y,z} and they participate in a relationship R and the instances in R

are: { (a,w), (b,w), (c,x), (d,x), (e,y) }. Which one of the following is correct?

- Cardinality ratio A:B is many-to-one; A participates partially; B participates completely.
- Cardinality ratio A:B is one-to-many; A participates completely; B participates partially.
- Cardinality ratio A:B is many-to-one; A participates completely; B participates partially.
- Cardinality ratio A:B is many-to-many; A participates completely; B participates partially.

Answer :-

12. A weak entity can exist even if it is not related to any other entity.

- True
- False

Answer :-

13. Key of an entity set can be determined by examining current entities in the set.

- True
- False

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14. A weak entity type can not be the owner of another weak entity type.

- True
- False

Answer :-

15. Weak entity type participates partially in the relationship that connects it to its owner.

- True
- False

Answer :-

16. Consider the following sets:

C = { p: weak entity type; q: multi-valued attribute; r: derived attribute: s: relationship type}

D = { w: dashed-line ellipse; x: diamond box; y: double-line rectangle; z: double-line ellipse}

The correct match between elements of C and D is:

- p — z; q — y; r — w; s — x
- p — y; q — z; r — x; s — w
- p — y; q — z; r — w; s — x
- p — x; q — w; r — z; s — y

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