 declare
 x exception;
 empnum emp.empno%type;
 pragma exception_init(x,-20100);
 begin
 update emp set ename='ALI' where empno=&empnum;
 if sql%notfound then
 raise_application_error(-20100,'Not updated....');
 end if;
 exception
 when x then
 dbms_output.put_line('empno does not exists');
 end;