Case

set serveroutput on;
DECLARE
    a NUMBER :=65;
    b NUMBER :=2;
    arth_operation VARCHAR2(20) :='MULTIPLY';
BEGIN
    dbms_output.put_line('Program started.' );
    CASE (arth_operation)
        WHEN 'ADD' THEN 
        dbms_output.put_line('Addition of the numbers are: '|| a+b );
        WHEN 'SUBTRACT' THEN 
        dbms_output.put_line('Subtraction of the numbers are: '||a-b ); 
        WHEN 'MULTIPLY' THEN 
        dbms_output.put_line('Multiplication of the numbers are: '|| a*b);
        WHEN 'DIVIDE' THEN 
        dbms_output.put_line('Division of the numbers are:'|| a/b);
        ELSE 
        dbms_output.put_line('No operation action defined. Invalid operation');
    END CASE;
    dbms_output.put_line('Program completed.' );
END;

--Searched case
DECLARE 
    a NUMBER :=70;
    b NUMBER :=2;
    arth_operation VARCHAR2(20) :='DIVIDE';
BEGIN
    dbms_output.put_line('Program started.' );
    CASE
        WHEN arth_operation = 'ADD' THEN 
            dbms_output.put_line('Addition of the numbers are: '||a+b );
        WHEN arth_operation = 'SUBTRACT' THEN 
            dbms_output.put_line('Subtraction of the numbers are: '|| a-b);
        WHEN arth_operation = 'MULTIPLY' THEN 
            dbms_output.put_line('Multiplication of the numbers are: '|| a*b ); 
        WHEN arth_operation = 'DIVIDE' THEN 
            dbms_output.put_line('Division of the numbers are: '|| a/b );
        ELSE 
            dbms_output.put_line('No operation action defined. Invalid operation'); 
    END CASE;
    dbms_output.put_line('Program completed.' );
END;