Example of equijoin, Database Management System

Example:

Consider the following relations:

ROLLNO

NAME

ADDRESS

COURSE_ID

100

Kanupriya

234, Saraswati Vihar.

CS1

101

Rajni Bala

120, Vasant Kunj

CS2

102

Arpita Gupta

75, SRM Apartments.

CS4

STUDENT

Course

COURSE ID

COURSE_NAME

DURATION

CS1

CS1

BCA

3yrs

CS2

MCA

3yrs

CS3

M.Sc.

2yrs

CS4

B.Sc.

3yrs

CS5

MBA

2yrs

 

 

 

If we want to show name of all the students with their course details then natural join is used in the following method:

STUDENT     COURSE

Resultant relation will be as follows:

If R2                    R3= R1 ÷ R2                      If R2                       R3= R1 ÷ R2

Student

ROLLNO

NAME

ADDRESS

COURSE_ID

COURSE_NAME

DURATION

100

Kanupriya

234, Saraswati

Vihar.

CS1

BCA

3yrs

101

Rajni Bala

120, Vasant Kunj

CS2

MCA

3yrs

102

Arpita

Gupta

75, SRM

Apartments.

CS4

B.Sc.

3yrs

 

 

 

 

 

There are some other types of joins like outer joins.

Posted Date: 3/6/2013 5:55:34 AM | Location : United States







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