give this a whirl...
[php]
<?
$connect = mysql_connect("localhost", "user", "pass");
$db = mysql_select_db("database", $connect);
$query = "DESCRIBE table_name column_name";
$result = mysql_query($query, $connect);
list($field, $type, $null, $key, $default, $extra) = mysql_fetch_array($result);
if ($extra == NULL)
{
echo "column does not auto-increment";
}
else
{
echo "column auto-increments";
}
?>
[/php]