准备好的语句和mysqli_query / mysqli_num_rows？

Question

I am trying to find out how to make my code work with prepared statements. I understood the entire process up to where I commented my code. What do I have to do in order to integrate num_rows and the mysqli_query part properly?

function login_check() {

    global $connection;

    $name = $_POST['name'];
    $password = $_POST['password'];

    $query = "SELECT id FROM members WHERE name = $name AND password = $password";
    $stmt = $connection->prepare($query);
    $stmt->bind_param('ss', $name, $password); 
    $stmt->execute();
    $stmt->close();

    // $result = mysqli_query($connection, $query);
    // $rows = mysqli_num_rows($result);

    if($rows > 0){
        header('location:../../success.php');
        exit;
    }

    else {
        header('location:../../failed.php');
        exit;
    }
}

What I tried:

$result = mysqli_query($connection, $stmt);
$rows = mysqli_num_rows($result);

Answer 1

Change

$query = "SELECT id FROM members WHERE name = $name AND password = $password";

to

$query = "SELECT `id` FROM `members` WHERE `name` = ? AND `password` = ?";

Adding backticks around table and columns prevents mysql reserved words error.

Remove $stmt->close();

if( $stmt->num_rows > 0 ) {
    $stmt->close();
    header('location:../../success.php');
    exit();
} else {
    $stmt->close();
    header('location:../../failed.php');
    exit();
}

Adding $stmt->close() inside if statement before header is best practice in this case. Becasue adding it before if statement would result in $stmt->num_rows always returning 0; Adding it after the if statment won't work because exit() would prefent it from executing.

From the documentation:

Closes a prepared statement. mysqli_stmt_close() also deallocates the statement handle. If the current statement has pending or unread results, this function cancels them so that the next query can be executed.