Decode function in Oracle

Decode facilitates conditional inquiries by working same as CASE or IF-THEN-ELSE statement.

Syntax :

DECODE (col|expression, search1, result1 [,search2,result2,...,] [,default])

Suppose I have a table called Employee with following data

Employee 
Firstname Lastname Jobcode salary 
Meena          Kumar      IT_PRG  10000
Kohil            Sharma    CLERK    5000
Ritu             Mehta       HR        12000

now using Decode function on this table

SELECT Lastname,Jobcode,salary,DECODE(Jobcode,'IT_PRG','1.10*salary', 'CLERK','1.15*salary','HR','1.20*salary') Revised_salary FROM Employee

Output

Lastname Jobcode Revised_salary 
Kumar      IT_PRG  11000
Sharma    CLERK    5750
Mehta      HR         14400