รบกวนดู code ให้ผมทีครับ ผมใส่ code check username ซ้ำ กันเข้าไปแล้วมันไม่ทำงานอะครับ มันยังซ้ำกันใน db อยุ่เลยครับรบกวนดูให้ผมทีน่ะครับ

<?
session_start();

include ("connect.php");

$e_id=$_POST['e_id'];
$e_first=$_POST['first'];
$e_name=$_POST['name'];
$e_lastname=$_POST['lastname'];
$e_sex=$_POST['sex'];
$e_address=$_POST['address'];
$e_tumbol=$_POST['tumbol'];
$e_aumper=$_POST['aumper'];
$e_province=$_POST['province'];
$e_zipcode=$_POST['zipcode'];
$e_idcard=$_POST['idcard'];
$e_tel=$_POST['tel'];
$e_username=$_POST['user'];
$e_password=$_POST['pass1'];
$e_status=$_POST['status'];




$sql = "SELECT e_id FROM tb_employee  ORDER BY  e_id DESC LIMIT 1";
      $result = mysql_query($sql);
      if(mysql_num_rows($result) > 0)
      {
           $row = mysql_fetch_array($result);
           sscanf($row[0] ,"E%d" , $id); 
		   $id++;
           $sql = "INSERT INTO tb_employee (e_id,e_first,e_name,e_lastname,e_sex,e_address,e_tumbol,e_aumper,e_province,e_zipcode,e_idcard,e_tel,e_username,e_password,e_status) VALUES(CONCAT('E',RIGHT(CONCAT('0000' , $id) , 4)) ,'$e_first','$e_name','$e_lastname','$e_sex','$e_address','$e_tumbol','$e_aumper','$e_province','$e_zipcode','$e_idcard','$e_tel','$e_username','$e_password','$e_status')"; 		   
      }
      else
      {
	  
$result_n=mysql_query("Select * From  tb_employee  Where e_username='$user' ");  *******  บรรทัดนี้ครับ   
$row=mysql_fetch_array($result_n);
if($row !=0 )
{
echo "<script>alert('ขออภัย username  นี้ถูกใช้งานแล้ว ');history.back();</script>";
} else {

} 

	  
 $sql = "INSERT INTO tb_employee(e_id,e_first,e_name,e_lastname,e_sex,e_address,e_tumbol,e_aumper,e_province,e_zipcode,e_idcard,e_tel,e_username,e_password,e_status)
		   VALUES('E0001','$e_first','$e_name','$e_lastname','$e_sex','$e_address','$e_tumbol','$e_aumper','$e_province','$e_zipcode','$e_idcard','$e_tel','$e_username','$e_password','$e_status')";
      }
	  
 
mysql_query($sql);
$affected_rows = mysql_affected_rows();

if ($affected_rows > 0) {
	echo"<meta http-equiv=\"refresh\" content=\"0;URL=admin_login.php\" />";
	
} else {	

	echo "<script>alert(' äÁèÊÒÁÒö·ÓÃÒ¡ÒÃä´é ');history.back();</script>";
	echo"<meta http-equiv=\"refresh\" content=\"0;URL=employee_add.php\" />";
}
mysql_close();

?>