3 Marks Each

Question 13 Marks

Differentiate between cardinality and degree of a table with the help of an example.

Answer

Cardinality is defined as the number of rows in a table.

Degree is the number of columns in a table.

Eg: Consider the following tables:

Supposing Table : Account contains 3 rows and 2 columns.

Cardinality of Account table is : 3

Degree of Account table is :2

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Question 23 Marks

Observe the following table and answer the parts (i) and (ii) accordingly

Table: Product

Pno	Name	Qty	PurchaseDate
101	Pen	102	12-12-2011
102	Pencil	201	21-02-2013
103	Eraser	90	09-08-2010
109	Sharpener	90	31-08-2012
113	Clips	900	12-12-2011

(a) Write the names of most appropriate columns, which can be considered as candidate keys.

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

Answer

Candidate Key: Pno, Name

Degree:4

Cardinality:5

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Question 33 Marks

What are candidate keys in a table? Give a suitable example of candidate keys in a table.

Answer

A table may have more than one such attribute/group of attribute that identifies a tuple uniquely, all such attribute(s) are known as Candidate Keys.

Table: Item

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Question 43 Marks

Differentiate between DDL & DMLcommands. Identify DDL & DML commands from the following:

(UPDATE, SELECT, ALTER, DROP)

Answer

DDL stands for Data Definition language and comprises of commands which will change the structure of database object.

DML stands for Data Manipulation Language and comprises of commands which are used to insert, edit, view & delete the data stored in a database object.

DDL Commands are: ALTER, DROP

DML Commands are: UPDATE, SELECT

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Question 53 Marks

Differentiate between Candidate Key and Alternate Key in context of RDBMS.

Answer

Candidate Key: It is the one that is capable of becoming primary key i.e.,a column or set of columns that identifies a row uniquely in the relation.

Alternate Key: A candidate key that is not selected as a primary key is called an Alternate Key.

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Question 63 Marks

Consider the table: CLUB as given below:

Table: CLUB

MEMBER_ID	MEMBER_NAME	ADDRESS	AGE	FEE
M002	NISHA	GURGAON	19	3500
M003	NIHARIKA	NEW DELHI	21	2100
M004	SACHIN	FARIDABAD	18	3500

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

(b) If a new column contact_no has been added and three more members have joined the club then how these changes will affect the degree and cardinality of the above given table.

Answer

(a) Degree = 5

Cardinality = 3

(b) After adding one more column Contact_no, then Degree is 6

After adding 3 more members Cardinality is 6.

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Question 73 Marks

Observe the table ‘Club’ given below:

Table: Club

Member_id	Member_Name	Address	Age	Fee
M001	Sumit	New Delhi	20	2000
M002	Nisha	Gurgaon	19	3500
M003	Niharika	New Delhi	21	2100
M004	Sachin	Faridabad	18	3500

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

(ii) If a new column contact_no has been added and three more members have joined the club then how these changes will affect the degree and cardinality of the above given table.

Answer

(i) Cardinality: 4

Degree: 5

(ii) Cardinality: 7

Degree: 6

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Computer Science 3 Marks Each

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