处理数据修改

我遇到了这样的情况。这是我的代码=>

while ($data = mysqli_fetch_assoc($result)){
                    echo "<tr>";
                        echo "<td><span class='getinfo'>" . $data['username'] . "</span></td>";
                        echo "<td></td>";
                        echo "<td><span class='getinfo'>" . $data['email'] . "</span></td>";
                        echo "<td></td>";
                        echo "<td><span class='getinfo'>" . $data['rights'] . "</span></td>";
                        echo "<td></td>";
                        echo "<td><span class='getinfo'>" . $data['last_seen'] . "</span></td>";
                        echo "<td></td>";
                        echo "<td><span class='getinfo'>" . $data['since'] . "</span></td>";
                        echo "<td></td>";
                        echo "<td><span class='getinfo'><select name='change_rights'><option value='sel'>* * *</option><option value='null'>0</option><option value='one'>1</option></select></span></td>";
                        echo "<td></td>";
                        echo "<td><span class='getinfo'><input type='submit' name='del_user' id='del_user' value='Delete'></span></td>";
                    echo "</tr>";
                }

如您所见，我在数据<select>和delete Submit之间做了介词这是一个

<form name="" action="" method="post"></form>

是否可以用<select>进行修改，并从脚本中删除这样的数据？如果可能，如何删除？或者不能建议我怎么做？

如果我有这样的html表单=>

<form name="mod" action="default.php" method="post">
    <input type="checkbox" name="mod[]" id="mod1">
    <input type="checkbox" name="mod[]" id="mod2">
        <input type="submit" name="ok" value="ok">
</form>

和php=>

if (isset($_POST['ok'])){
    if ($_POST['mod']=="mod1"){
        echo "one";
    } else {
        echo "two";
    }
}

（我从来没有用php使用过复选框，我也不太了解它）有些事情进展不顺利，这里出了什么问题？