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Relational Database

Description: Relational Database contains concept based questions of SQL, Database for Information Technology
Number of Questions: 15
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Which of the following is/are not known as attribute type in a relation?

  1. Composite

  2. Single - valued

  3. Derived

  4. Unary

  5. Simple


Correct Option: D
Explanation:

This is the correct answer. There are five types of attributes in database. These are :-1.) Simple attribute 2.) Composite attribute 3.) Single-valued attribute 4.) Multivalued attribute 5.) Derived attributeThere is no attribute named unary. Unary is a type of relation which is known as degree of relation(unary, binary, ternary etc.). So this is the correct answer according to the question.

In how many types the connectivity of a relationship can be classified?

  1. 8

  2. 6

  3. 4

  4. 5

  5. 3


Correct Option: C
Explanation:

This is the correct answer. Connectivity means how many instances of one entity are associated with how many instances of other entity.The connectivity of a relationship can be classified in 4 types. These are :-1.) One to one (1 : 1)2.) One to many (1 : M)3.) Many to one (M : 1)4.) Many to many(M : N)So this answer is also correct.

Which of the following entity sets do not have a primary key?

  1. Composite entity set

  2. Weak entity set

  3. Strong entity set

  4. Derived entity set

  5. None of these


Correct Option: B
Explanation:

This is the correct answer. The entity set that doesn’t have sufficient attributes to form a primary key and relies on another for its identification is called a weak entity set. It doesn’t have a primary key.So this is correct answer.

A relationship can be classified in terms of which of the following?

  1. Degree

  2. Connectivity

  3. Composition

  4. Both 1 and 3

  5. All of the above


Correct Option: D
Explanation:

As I explained the reason both options 1 & 3 are correct.So this is the correct choice.

What are the members of weak entity set called?

  1. Subordinate entity

  2. Dominant entity

  3. Compound entity

  4. Derived entity

  5. None of these


Correct Option: A
Explanation:

This is the correct answer. There is no particular reason to explain this answer, because there is a name convention in DBMS. The members of weak entity set are called subordinate entity set.So this is the correct answer.

How many types of record based data models are there in database?

  1. 6

  2. 5

  3. 4

  4. 3

  5. 2


Correct Option: D
Explanation:

This is correct answer. There are 3 types of record based data models. These are :-1.) Hierarchical model2.) Network model3.) Relational modelThese are the 3 models.So this is the correct choice.

P : Foreign key cannot have a null value. Q : Primary key and foreign key can exist in same relation. R : Foreign key relation is known as target relation.

Which of the given statements are true?

  1. Q only

  2. P only

  3. Both P and Q

  4. Both P and R

  5. R only


Correct Option: A
Explanation:

This is true choice. Q statement is correct because the primary key and the foreign key can exist in the same relation. Moreover foreign key can refer to the primary key in the same relation.So this is correct choice.

P : Total number of tuples at any one time is known as degree of a relation. Q : Total number of columns that comprise a relation is known as cardinality of a relation. R : Restrictions can be applied on the value of attributes.

Which of the given statements is/are correct?

  1. Both P and Q

  2. R only

  3. None of these

  4. All of these

  5. Both P and R


Correct Option: B
Explanation:

This is correct choice. Statement R is true because we can apply restrictions on values of attributes these are known as constraints.So this answer is correct.

How many types of attributes are there in relational database?

  1. 6

  2. 5

  3. 4

  4. 3

  5. None of these


Correct Option: B
Explanation:

There are five types of attributes in database. These are :-1.) Simple attribute2.) Composite attribute 3.) Single-valued attribute4.) Multivalued attribute5.) Derived attribute So this is the correct answer .

How many types of data models are present in DBMS?

  1. 5

  2. 4

  3. 3

  4. 2

  5. None of these


Correct Option: B
Explanation:

This is the incorrect answer. there are 3 types of data models present in DBMS. These are :-1.) Object based data model2.) Record based data model3.) Physical data modelSo this is the incorrect answer.

Which of the following operations is/are unary operations?

  1. Union

  2. Selection

  3. Projection

  4. Both 2 and 3

  5. All of these


Correct Option: D
Explanation:

As I explained both 2 & 3 options are correct. So this is correct choice.

How many types of keys are there in relational database?

  1. 9

  2. 7

  3. 8

  4. 6

  5. None of these


Correct Option: B
Explanation:

This is the correct answer. There are seven types of keys in relational database. These are :-1.) Primary key2.) Candidate key3.) Super key4.) Foreign key5.) Alternate key6.) Artificial key7.) Composite keySo this is the correct answer.

P : Candidate key cannot be null. Q : If the primary key is composed of more than one attribute, then these attributes are known as super attributes. R : All the candidate keys can be primary key.

Which of the given statements is/are correct?

  1. P only

  2. Both P and Q

  3. Both P and R

  4. Both Q and R

  5. All of these


Correct Option: C
Explanation:

Option P is correct because a candidate key is a key that uniquely identifies a row in a relation. So this cannot be null as it uniquely identifies a row.Option R is correct because primary key is chosen from a set of candidate keys. In other words all the candidate keys are the candidates for the primary key. So in this way all the candidate keys are primary keys.So this is the correct answer.Option Q is false because If the primary key is composed of more than one attribute then these attributes are known as prime attributes not super attributes.

Which of the following operations is/are known as binary operations?

  1. Intersection

  2. Cartesian product

  3. Difference

  4. Both 2 and 3

  5. All of these


Correct Option: E
Explanation:

As I explained that all of the given options are true. So this is correct choice.

What are the members of strong entity set called?

  1. Dominant entity

  2. Derived entity

  3. Subordinate entity

  4. Composite entity

  5. None of these


Correct Option: A
Explanation:

This is the correct answer. There is no particular reason to explain this answer, because there is a name convention in DBMS. The members of strong entity set are called dominant entity set.So this is the correct answer.

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