PHP MYSQL更新查询不起作用

大家好，

我目前正在您登录的网站上工作，它需要更改用户名的一部分.

我的更新查询似乎还可以，但是我的php却不行:

Hi everyone,

I''m currently working on a website that you log into, and it needs a changing username part of it.

My update query seems to be ok, but my php is not:

<?php

$con = mysql_connect("~-~-~-~","~-~-~-~","~-~-~-~");

if (!$con){
    die('Could not connect: ' . mysql_error());
}

mysql_select_db("~-~-~-~", $con);

$username_update = mysql_query("UPDATE users SET username='" . $_GET['confirm_username'] . "' WHERE username='$my_username'");

$username_select = mysql_query("SELECT username FROM users WHERE username = '" . $_GET['confirm_username'] . "'");

$row = mysql_fetch_array($username_select);

if (!$row = $my_username){
    ?>
        <div id="username_changed_green">
            Username Changed
        </div>
    <?php
}else{
    ?>
        <div id="incorrect_details_username">
            Incorrect Details
        </div>
    <?php
}
mysql_close($con);
?>

在网站上线时，会显示错误的详细信息框，有任何建议吗?

问候，
Tom.

On the website when it is live, the incorrect details box just shows, any suggestions?

Regards,
Tom.