只需单击一次提交即可刷新页面

所以我有下面的代码。我的问题是，要使"vous êtes amis"消息出现，用户必须在提交按钮上单击两次。但是我想让用户只在提交按钮上单击一次。谢谢！

       <?php
       $checkcontact = mysql_query("SELECT * FROM contacts WHERE IDcontact = '".$dnn['id']."'");
       if(mysql_num_rows($checkcontact) == 1)
           {
           echo "<h1>Vous êtes amis</h1>";
           }
           else
           {
       ?>
<form method="post" action="profile.php?id=<?php echo $dnn['id']; ?>">
    <input type="hidden" value="<?=$dnn['Username'];?>" name="userid" />
    <input type="submit" value="Add as Friend" />
</form>

<?php
if ($_POST)
{  
  $fid = htmlspecialchars(stripslashes($_POST['userid']));
  $fid = mysql_real_escape_string($fid);
      include("base.php");
      mysql_query("INSERT into contacts (ID, Nom, IDcontact, Nomcontact) VALUES ('".$_SESSION  ['id']."', '".$_SESSION['Username']."', '".$dnn['id']."', '$fid')");
      }
}
?>