- A constant is a value used in a PL/SQL block which remains unchanged throughout the program.
- It can be declared and used instead of actual values.
For example: Assume if programmer has to write a program which will increase salary of the employee upto 10%. So programmer can declare a constant and use it throughout the program.
Constant_name CONSTANT datatype := value;
Lets take an example to understand the declaration and execution of constants.
Example
DECLARE
-- constant declaration
pi constant number := 3.14;
-- other declarations
radius number(6,2);
dia number(6,2);
circumference number(8, 2);
area number (11, 2);
BEGIN
-- processing
radius := 3.5;
dia := radius * 2;
circumference := 2.0 * pi * radius;
area := pi * radius * radius;
-- output
dbms_output.put_line('Radius: ' || radius);
dbms_output.put_line('Diameter: ' || dia);
dbms_output.put_line('Circumference: ' || circumference);
dbms_output.put_line('Area: ' || area);
END;
/
Output:
Radius: 3.5
Diameter: 7
Circumference: 21.98
Area: 38.465
