Question

I am learning some myqli and would like to make a simple check.

Basically, A user will enter their email addess then submit a form, if the email address is already contained in a certain mysql table, then the script must stop with an error.

This is my example:

$userEmail = sanitize($_POST['specials']);          
// Check to see if email already exists, if not proceed
if ($stmt = $link->prepare("SELECT email FROM specials WHERE email=$userEmail"))
{
    $specialsErrorFocus = 'autofocus="autofocus"';
    $specialsInfo = 'This email address: $userEmail, is already in our database.';
    include "$docRoot/html/shop/home.html.php";
    exit();
}

This code does not do as I have intended it to as described.

Could someone please explain where I am going wrong with this, or possibly offer a better solution for this task.

Thanks in advance!

Answer 1

You need to execute the query first, as simply preparing the statement is not sufficient. See the documentation as it is a multi stage process.

First, you prepare the statement:

$stmt = $link->prepare("SELECT `email` FROM `specials` WHERE `email` = ?")
if (!$stmt) {
   echo $link->errno . " : " . $link->error;
}

Next, bind the parameters:

if (!$stmt->bind_param("s", $userEmail)) {
    echo $stmt->errno . " : " . $stmt->error;
}

Finally, execute the query:

if (!$stmt->execute()) {
    echo $stmt->errno . " : " . $stmt->error;
}

Get the results:

$stmt->store_result();

if ($stmt->num_rows) {

   # Email exists
}