Question 4 - Past Year - 2 Mark Questions - Chapter 8 - Database Concepts

Last updated at April 16, 2024 by

Observe the following table and answer the parts

(i) and (ii):

 

(i) In the above table, can we have Qty as primary key.

 

Answer:

Primary key refers to a set of one or more attributes which can uniquely identify tuples in a relation.

 

In the above table, there is a duplication of values in the column Qty. So the attribute Qty cannot uniquely identify the tuples in a relation. Hence, we cannot set Qty as the primary key.

 

(ii) What is the cardinality and degree of the above table?

 

Answer:

  • Cardinality refers to the number of tuples/rows in a table. 
  • Degree refers to the number of attributes/columns in a table.

So for the above table,

Cardinality = 5

Degree = 4

 

 

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Transcript

Observe the following table and answer the parts (i) and (ii): (i) In the above table, can we have Qty as primary key. Answer: Primary key refers to a set of one or more attributes which can uniquely identify tuples in a relation. In the above table, there is a duplication of values in the column Qty. So the attribute Qty cannot uniquely identify the tuples in a relation. Hence, we cannot set Qty as the primary key. (ii) What is the cardinality and degree of the above table? Answer: Cardinality refers to the number of tuples/rows in a table. Degree refers to the number of attributes/columns in a table. So for the above table, Cardinality = 5 Degree = 4

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo