Php Help Please

[acey]

okie ... this is for a chat room im working on and the problem is the private messaging .. ok it works tho

i use this for user selection .. whom to send a private message too

<select name=\"who\">";

  $sql = "SELECT username FROM online where room='$id' and username!='$uid' ORDER BY username ";

$result = mysql_query($sql);

if (!$result) {	

    error('A database error occurred in processing your '.

          'submission.\\nIf this error persists, please '.

          '[e-mail]');

}

  $num=mysql_numrows($result);

$i=0;

while ($i < $num) {

$username=mysql_result($result,$i,"username");

echo"

<option value=\"$username\">$username</option> ";

++$i;

}

echo"

</select>

and posting that form ...

if no users are online appart from urself if shows up blank (thats what i want) but ...

the next page .. the chat display page i use

$who=$_POST['who'];

being the username

and before the private message being inserted to the database have the following

if ($who==' '){

}

but it goes ahead and does it anyway ... can anyone help please ?