PHP条件使用其他值不正确

Question

I am writing a conditional in PHP to check if certain user credentials have been used, and am using an if....elseif....else conditional method to do it. In each statement, I am defining the value of a variable if that statement is true. No matter what, the else value is always being used.

Also, if you want brownie points, would this be easier to do with a switch statement?

$username = $_POST['username'];
$password = strong_crypt($_POST['password'] . $username );
$name = $_POST['name'];
$email = $_POST['email'];

while($row = mysqli_fetch_array($query))
{
    $allEmails = $row['email'];
    $allUnames = $row['uname'];
}

if($allEmails === $email)
{
    $message = "That email already exists. You can only have one account per email address.";
}
elseif($allUnames === $username)
{
    $message = "That username has already been taken. Please choose a different one.";
}
elseif($username === null || $email === null || $password === null || $name === null) 
{
    $message = "Please fill out all fields to register";
}
else
{
    mysqli_query($conn, "INSERT INTO login (name, uname, pword, email, lat, lon, it) VALUES ('$name', '$username', '$password', '$email', '$lat', '$lon', '$it')");
    $message = "goodtogo";
}

Answer 1

It appears the issue here is that you're doing the checks outside of the while loop, so that the check will always be done against the values from the LAST row of your query. Perhaps this code is more what you were aiming for?

$username = $_POST['username'];
$password = strong_crypt($_POST['password'] . $username );
$name = $_POST['name'];
$email = $_POST['email'];
$message = '';

if($username === null || $email === null || $password === null || $name === null) 
{
    $message = "Please fill out all fields to register";
}
else
{
    while($row = mysqli_fetch_array($query))
    {
        $allEmails = $row['email'];
        $allUnames = $row['uname'];

        if($allEmails === $email)
        {
            $message = "That email already exists. You can only have one account per email address.";
            break;
        }
        else if($allUnames === $username)
        {
            $message = "That username has already been taken. Please choose a different one.";
            break;
        }
    }
}
if (!$message)
{
    mysqli_query($conn, "INSERT INTO login (name, uname, pword, email, lat, lon, it) VALUES ('$name', '$username', '$password', '$email', '$lat', '$lon', '$it')");
    $message = "goodtogo";
}