GATE CSE 2023 | Question: 6

Question

Which one of the options given below refers to the degree (or arity) of a relation in relational database systems?

• A. Number of attributes of its relation schema.
• B. Number of tuples stored in the relation.
• C. Number of entries in the relation.
• D. Number of distinct domains of its relation schema.

Comments

Option a is correct

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Arity == Degree == No.  of Col. == Attribute == Property == Field
Option A is correct

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Option A because degree can known by counting the attributes of a relation and cardinality can be counted by number of rows of present instances or relation or table.

Answer 1

Relational Model Definitions:

A relation is a table with columns and rows.

An attribute is a named column of a relation.

A tuple is a row of a relation.

A domain is a set of allowable values for one or more attributes.

The degree of a relation is the number of attributes it contains.

The cardinality of a relation is the number of tuples it contains.

A relational database is a collection of normalized relations with distinct relation names.

The intension of a relation is the structure of the relation including its domains.

The extension of a relation is the set of tuples currently in the relation.

Relational Model - Terminology & Basic Concepts

Comments

@Deepak PooniaSir Can u tell how to obtain the brekeley university lecture slides 

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Arity in general used to tell the number of operands. For example arity of a functions f(x), g(x,y) are 1 and 2.

Cardinality is used to tell the number of things [in a set]. A relation in RDBMS is a set of tuples.

Answer 2

Degree in a relational database is simply the number of attributes in relations.

Option (A) is correct.

Comments

yeah that's true and if we're not careful then we might do that silly mistake by choosing option D because it looks like it's true and if we go with the definition of degree of relation then only we can choose Option A 

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So true, We need to even know the proper defination of Domain for not getting confused

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Answer is Option A

Answer 3

I dont know how was this question even given in the exam :)

Anyways answer is option a

Comments

grace marks hoga

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How ?

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I mean it's easy to score @buntyprasadnayak

Answer 4

The degree (or arity) of a relation in a relational database system refers to the number of attributes or columns in its relation schema. It indicates how many pieces of information are associated with each tuple (row) in the database table.

Correct Answer: Option (A) ->Number of attributes of its relation schema.

Comments

What about D?

 

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option D fails because if there's a table that contains

 student{ name: string $student \left \{ name : string, age: int, subject : int,marks:int , address:string \right \}$, age,address,marks}$Here\,actually\,we've\,5 \,attributes/columns\, but\,as\,per\,option D\, it\,counts\,the\,degree\,as\,\, 2.$

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for two columns we may have same domain so d is incorrect ,deg =total no of coloumns/attributes A is correct ans

Answer 5

Option A The number of attributes of its relation schema is the degree ( or arity) of a relation . B,  C options refer to the cardinality of the relation.  D . Number of distinct domains in the relation means every attribute of the relation has a domain and the conditions of this domain for every attribute has to be different from each other . However we donot call this degree . Degree is the total number of attributes/ columns / fields in any relation R

Answer 6

The correct answer is: A. Number of attributes of its relation schema.Explanation: 

 

The degree (or arity) of a relation in a relational database system refers to the number of attributes (columns) in the relation's schema. This is a fundamental concept in relational database theory, where the degree is used to describe the structure of the relation. 

Other options are incorrect because:- B refers to the number of tuples (rows), which is not the definition of degree.- 

C refers to the total number of entries, which is not the definition of degree.-

  D refers to the number of distinct domains, which is not the definition of degree.