php while循环 selecrt下拉框 option默认选中

<?php

$sql = "SELECT id FROM signinconfday ";
$res = mysql_query($sql, $news);
while ($date = mysql_fetch_assoc($res)) {
    ?>
    <option value=<?php echo $date['id']  ?> <?php if ($date['id'] =="参数二") {echo "selected=\"selected\"";} ?>>
        <?php echo $date['id']  ?></option>


    <?php} ?>