将用户定向到另一个页面（PHP和MysQL）

I am creating a site where invited users will be directed to a register once their email is validated against a master list of users and (2) returning users will be directed to a different page once validated against a master list of users. Initially the master list of users will only have email addresses for the invited users. Upon registration, users will enter the rest of the information, including First Name (fname).

What I need to do with this piece of code is check if the first name is NULL, if so direct user to "registration.html"; whereas if a first name is present for that user then the user should be directed to "overview.html".

My code is clearly not working properly, as regardless of fname being NULL or XYZ users are directed to "overview.html".

$query = "SELECT email, fname FROM registration WHERE email='$email'";

   if (fname = "NULL") {
       header('location: registration.html');
   } else {
       header('location: overview.html');
   }

Thanks for your help!

I'm assuming you didn't paste the whole code here. How did you fetch the row?

One thing I can point out though, in PHP = is assignment.You want to use == which is the comparison operator.

Also, unquote "NULL", as you're currently comparing it to a string 'null'.

Hope that solves it.

EDIT: seeing your other comments, here's what the code should look like, assuming you have the email stored in a variable called $email and a PDO connection stored in $dbc.

$q = "SELECT email, fname FROM registration WHERE email = ?";
$stmt = $dbc->prepare($q);
$stmt->execute(array($email));
if($stmt->rowCount() == 1){ //you probably have unique email accounts
    $row = $stmt->fetch();
    if (is_null($row['fname'])) {
        header('location: registration.html');
    } else {
        header('location: overview.html');
    }
}