declare
	x number;
begin
	select count (*) into x from student_t where student_t.student_id= :xstudent_id;
		if x > 0 then
			select student_t.first_name,student_t.last_name,student_t.course 
			into :xfirst_name, :xlast_name, :xcourse from student_t where student_id= :xstudent_id;
		end if;
end;

DECLARE
  v_return PLS_INTEGER;
BEGIN
  SELECT s.first_name
       , s.last_name
       , s.course 
    INTO :yourblock.xfirst_name
       , :yourblock.xlast_name
       , :yourblock.xcourse 
    FROM student_t 
   WHERE student_id= :xstudent_id;
EXCEPTION
  WHEN NO_DATA_FOUND THEN
    v_return := SHOW_ALERT(youralert);
END;