Try something like this:
<td><div align="right">
<SELECT name="menu">
<?php
$conn = odbc_connect("HOMES", "", "");
$billdate = $_POST[ 'billdate' ];
$q_menu = "SELECT DISTINCT sls_his_cust_id FROM sls_his where
sls_his_prchdat_alt = $billdate";
$r_menu = odbc_exec($conn, $q_menu);
while ($rec_menu = @odbc_fetch_array($r_menu)) $menu[] = $rec_menu;
echo "<OPTION value=\"\">--SELECT--</OPTION>\n";
foreach ($menu as $m)
{
if ($m['sls_his_cust_id'] == $_POST['menu'])
echo "<OPTION value=\"{$m['sls_his_cust_id']}\"
SELECTED>{$m['sls_his_cust_id']}</OPTION>\n";
else
echo "<OPTION
value=\"{$m['sls_his_cust_id']}\">{$m['sls_his_cust_id']}</OPTION>\n";
}
?>
</SELECT>
</td>
