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## Renames Operation ( ρ )

Consider the following expression.

ρx (E)

Here, this operator gives the name ‘x’ to the result of the relational algebra expression E.

Consider the following relation

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

Example-1: Execute the following SQL expression.

ρx (P Qual (Faculty-1)

Output :    Qual

Ph.D.

MTech

Example-2 : Find the names of Ph.D. holders in a new relation named ‘F-PhD’.

ρ F-Ph.D. (P FName(squal  = ‘Ph.D.’ (Faculty-1) )

Output :    F-PhD

FName

Riya

Max

Fred

Example-3: Find the Salaries of  Ph.D. holders belonging to DNo = 24, under a new relation named ‘Sal-PhD-24’.

ρ Sal-PhD-24. (P Salary(squal  = ‘Ph.D.’ (Faculty-1) )˄ DNo = 24

Output :  Sal-PhD-24

Salary

53000

52000