DECLARE   
       a number(3) := 500;   
    BEGIN   
       -- check the boolean condition using if statement    
       IF( a < 20 ) THEN   
          -- if condition is true then print the following     
          dbms_output.put_line('a is less than 20 ' );   
       ELSE   
          dbms_output.put_line('a is not less than 20 ' );   
       END IF;   
       dbms_output.put_line('value of a is : ' || a);   
    END;  

    DECLARE   
       a number(2) := 20;   
    BEGIN   
       -- check the boolean condition using if statement    
       IF( a < 20 ) THEN   
          -- if condition is true then print the following     
          dbms_output.put_line('a is less than 20 ' );   
       ELSE   
          dbms_output.put_line('a is not less than 20 ' );   
       END IF;   
       dbms_output.put_line('value of a is : ' || a);   
    END;  

    DECLARE   
       a number(3) := 500;   
    BEGIN   
       -- check the boolean condition using if statement    
       IF( a < 20 ) THEN   
          -- if condition is true then print the following     
          dbms_output.put_line('a is less than 20 ' );   
       ELSE   
          dbms_output.put_line('a is not less than 20 ' );   
       END IF;   
       dbms_output.put_line('value of a is : ' || a);   
    END;