Lets say drop down 1 holds the leagues and drop down 2 holds the teams:
<?php
echo '
<select name="league" id="dd1" onchange="changeLeague()">';
foreach ($leagues AS AS $league)
echo '
<option value="', $league['id'], '">', $league['name'], '</option>';
echo '
</select>
<select name="team" id="dd2">
<option value="-1">Choose a league!</option>
</select>
<script type="text/javascript"><!-- // --><![CDATA[
function changeLeague()
{
var dd2 = document.getElementById("dd2");
clearOptions(dd2);
switch(document.getElementById("dd1").value)
{';
foreach($leagues AS $league)
{
echo '
case ', $league['id'], ':';
foreach($league['teams'] AS $id => $name)
echo '
addOption(dd2, ', $id, ', "', $name, '");';
}
echo '
}
}
function clearOptions(ele)
{
while (ele.length)
ele.remove(0)l
}
function addOption(ele, value, text)
{
var nextopt = document.createElement("option");
nextopt.value = value;
nextopt.text = text;
ele.add(nextopt, null);
}
]]></script>';