user vergelijke

$query = "SELECT user, email FROM leden";
$result = mysql_query($query);
$row = mysql_fetch_array($result,MYSQL_ASSOC);
if (isset($_SESSION['user']))
{
	echo 'Je bent al ingelogd!';
}
else
{
	if (isset($_POST['register']))
	{ 
		if
		($_POST['user'] == $row['user'] OR 
		$_POST['email'] == $row['email'])
		{
		echo 'Username of email bestaat al!';
		}

$query = "SELECT user, email FROM leden";
$result = mysql_query($query);
$row = mysql_fetch_array($result,MYSQL_ASSOC);
if (isset($_SESSION['user']))
{
	echo 'Je bent al ingelogd!';
}
else
{
	if (isset($_POST['register']))
	{ 
		if
		($_POST['user'] == $row['user'] OR 
		$_POST['email'] == $row['email'])
		{
		echo 'Username of email bestaat al!';
		}

<?php
$rOphalen = 'SELECT username FROM leden WHERE username = '.$_POST['veldnaam'];

if (MySQL_Query($rOphalen))
{
      if (MySQL_Num_Rows($rOphalen) == true)
      {
            echo 'lid bestaat al';
      }
}
?>'

<?php
$rOphalen = 'SELECT username FROM leden WHERE username = '.$_POST['veldnaam'];
 
if (MySQL_Query($rOphalen))
{
      if (MySQL_Num_Rows($rOphalen) == true)
      {
            echo 'lid bestaat al';
      }
}
?>'

<?php
$qophalen = "SELECT * FROM leden WHERE username = '".$_POST['veldnaam']."'";
$raw = mysql_query($qophalen)
      if(mysql_num_rows($raw) != 0){
            echo("lid bestaat al");
      }else{
            //alles ok
      }
mysql_close();
?>

<?php
$qophalen = "SELECT * FROM leden WHERE username = '".$_POST['veldnaam']."'";
$raw = mysql_query($qophalen)
      if(mysql_num_rows($raw) != 0){
            echo("lid bestaat al");
      }else{
            //alles ok
      }
mysql_close();
?>