Say I have 5 IP address in a table.
I get the records and put it in a <select>-drop down using PHP:
if ($myrow = mysql_fetch_array($result)) {

echo "<select name='setiph$i'>";

do {
echo "<option>";
echo $myrow["IPAddress"];
echo "</option>";

} while ($myrow = mysql_fetch_array($result));

echo "</select>";
} else {
echo "Sorry, no records were found!";

Thus there will be 5 values in the select.
Eg Say on this page display 5 computer that the user needs to assign IP address to. I would like it to alert user if the user has selected the same IP address for one computer when he has selected that for another one already
Eg comp1:
comp2: Any IP beside if user still selects this, alert.

In another words, for each computer, I need to check whether that IP was selected already through the drop down.If yes, alert, if no nothing I guess. How can I do this? Pls provide an example. What language can be used-PHP,Javascriptetc...?

Hope you get what I mean. Hope someone can help me.I am really new at this.Thanks