join mysql 3 table แล้วแสดงข้อมูลจาก table1 แต่ไม่มีอะไรขึ้นมาเลย

SELECT
  m4_announce2015.id_anounce_exam,
  name_anounce_exam.id_anounce_exam,
  m4value.id_anounce_exam
FROM m4_announce2015
inner join  name_anounce_exam
   on m4_announce2015.id_anounce_exam = name_anounce_exam.id_anounce_exam
inner join  m4value
   on name_anounce_exam.id_anounce_exam = m4value.id_anounce_exam

where m4_announce2015.iden_exam = '$numberexam'
AND m4_announce2015.iden_ppl = '$identy'
AND m4_announce2015.id_anounce_exam = 2

<?php
include("connect.php");
		$sql="SELECT
  m4_announce2015.id_anounce_exam,
  name_anounce_exam.id_anounce_exam,
  m4value.id_anounce_exam
FROM m4_announce2015
inner join  name_anounce_exam
   on m4_announce2015.id_anounce_exam = name_anounce_exam.id_anounce_exam
inner join  m4value
   on name_anounce_exam.id_anounce_exam = m4value.id_anounce_exam
";
				
		

		$result_st=mysql_query($sql);
        $num=mysql_num_rows($result_st);	
		$row=mysql_fetch_array($result_st);	

print_r();		
?>

<?php
include("connect.php");
		$sql="SELECT
  m4_announce2015.id_anounce_exam,
  name_anounce_exam.id_anounce_exam,
  m4value.id_anounce_exam
FROM m4_announce2015
inner join  name_anounce_exam
   on m4_announce2015.id_anounce_exam = name_anounce_exam.id_anounce_exam
inner join  m4value
   on name_anounce_exam.id_anounce_exam = m4value.id_anounce_exam
";
				
		

		$result_st=mysql_query($sql);
        $num=mysql_num_rows($result_st);	
		$row=mysql_fetch_array($result_st);	

print_r($row);		
?>