insert the email id its not exit; if exit only update the row do not insert again

[himrai06]

i have table in which first time insert the value in table
and second time when i was login with same email update row did no insert again.
my problem is that when i was my query my table is updated but insert once again the in next row;
i want that only update did not insert again
please solve my problem as soon as possible for you
here i am sending my php code below

if(!isset($_SESSION['user']))
{
    header("Location: ../index.php");
}
 
$email=$_SESSION['user'];
$res=mysql_query("SELECT * FROM user_businessleads WHERE user_email='$email'");
$row=mysql_fetch_array($res);
 
  if(isset($_POST['submit']))
  {
       $looking_for = $_POST['looking_for'];
        $services = $_POST['services'];
        $mybudget = $_POST['mybudget'];
        $around = $_POST['around'];
        $s_reguirement = $_POST['s_reguirement'];
        $chk="";
    $email=$_SESSION['user'];  
     foreach($services as $chk1)  
   {  
      $chk .= $chk1.",";
 
}
 
       $query=mysql_query("INSERT INTO user_businessleads(services,user_email,looking_for,mybudget,around,s_requirment)values('$chk','$email','$looking_for','$mybudget','$around','$s_reguirement')"); 
}
 if(isset($_POST['submit']))
  {
       $looking_for = $_POST['looking_for'];
        $services = $_POST['services'];
        $mybudget = $_POST['mybudget'];
        $around = $_POST['around'];
        $s_reguirement = $_POST['s_reguirement'];
        $chk="";
    $email=$_SESSION['user'];  
     foreach($services as $chk1)  
   {  
      $chk .= $chk1.",";
 
}
 $updated=mysql_query("UPDATE user_businessleads SET services='$chk',looking_for=' $looking_for',mybudget='$mybudget',around='$around',s_requirment='$s_reguirement' WHERE user_email='$email'")or die;
}
?>