$ _POST返回一个空值

Question

我尝试使用以下代码行来验证个人身份并更新其电子邮件地址，但代码将电子邮件的值读取为空白，并将其更新为数据库中的空白。

<form method="post">
    <input type="hidden" name="__token" value="exex"/>
    <div class="row">
        <label for="email">Email address</label>
        <div><input type="email" id="email" name="email" value="<?php echo $email; ?>"/></div>
        <br/>
        <div class="notice">Used for lost password recovery. Important!</div>
    </div>
    <div class="row">
        <label for="newpass">New password</label>
        <div><input type="password" id="newpass" name="newpass"/></div>
        <br/>
        <div class="notice">Leave empty if you do not want to change it.</div>
    </div>
    <div class="row">
        <label for="curpass">Current password</label>
        <div><input required type="password" id="curpass" name="curpass"/></div>
        <br/>
        <div class="notice">You must enter your current password to save the settings.</div>
    </div>
    <div class="row"><input type="submit" value="Save settings"/></div>
</form>

提交后，在同一页面（设置）中：

if(isset($_POST['email']) && (isset($_POST['curpass']) && $_POST['newpass'] == "")) {
    $email = mysql_real_escape_string($_POST['email']);
    $curpass = strtoupper(hash("whirlpool", $_POST['curpass']));
    $passii = $con->query("SELECT `password` FROM `playerinfo` WHERE `PlayerName` = '{$_SESSION['playername']}';");
    while($row = $passii->fetch()) {
        $curpass1 = $row['password'];
    }
    if($curpass == $curpass1) {
        echo "<div class='flash_success'>Your email has been changed.</div>";
        $con->query("UPDATE `playerinfo` SET `email` = '$email' WHERE `PlayerName` = '{$_SESSION['playername']}'");
    } else {
        echo "<div class='flash_error'>You did not enter your current password correctly. Settings were not saved.</div>";
    }
}