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Set Difference, Set Intersection, Cartesian Product Operations

Lets us understand these operations with some examples:

Consider the following table:

R1 :    FACULTY-1

 FNo FName DNo Qual Salary 22 Riya 21 Ph.D 55000 24 Priya 22 M. Tech 50000 25 Zayn 22 M. Tech 42000 27 Harry 23 M. Tech 28000 30 Sia 23 M. Tech 32000 33 Max 24 Ph.D 53000 35 Fred 24 Ph.D 52000 37 Diva 25 M. Tech 26000 39 Ben 25 M. Tech 24000 40 Trent 25 M. Tech 34000

Set Difference Operation ( U ):

‘Set difference’ operation eliminates second relation data from first relation data.

Example-1 : Find the tuples only in Dno = 23,  but they should not be in DNo = 25.

sDNo = 23 (Faculty-1)  –  sDNo = 25 (Faculty-1)

Output :

 FNo FName DNo Qual Salary 27 Harry 23 M. Tech 28000 30 Sia 23 M. Tech 32000

Set Intersection Operation ( Ç ):

‘Set intersection’ operation takes only common tuples from both the relations.

Example-1: Find the tuples which are in both Dno = 23 and DNo = 25.

sDNo = 23 (Faculty-1)  Ç sDNo = 25  (Faculty-1)

Output : No Output

Cartesian Product Operation ( X ):

This operation combines every tuple from relation-1 with every tuple from relation-2.

Consider the following relations :

 R1 :  STUD R2 : DEPT SNo SName DNo DNo DName 21 Riya 21 21 CSE 23 Priya 21 22 IT 26 Zayn 22 23 ECE 28 Harry 22 24 ME 30 Sia 23 25 EEE

Example-2 : Combine the above two relations with Cartesian product operators.

STUD   X   DEPT

Output : Here every tuple in STUD is combined with every tuple in DEPT. There will be a total of 25 tuples and 5 attributes.