Question

This piece of code returns 1 every time even if there is no given email address in db table. As you I place die($count) right after bind_result. It returns 1 every time. Have you noticed any wrong in my code?

    $stmt = $db->prepare("SELECT COUNT(id) FROM `users` WHERE `email`=? LIMIT 1") or die($db->error);
    $stmt->bind_param("s", $email) or die ($stmt->error);
    $stmt->execute() or die ($stmt->error);
    $count=$stmt->bind_result($count) or die ($stmt->error);
            die($count);
            $stmt->close();
    return ($count > 0 ? true : false);

Answer 1

You didn’t call $stmt->fetch() to put the result of the query into the bound variable $count.

The value of $count is therefore set to the return value of $stmt->bind_result() which is always true (1) or false (0).

See examples at http://php.net/manual/en/mysqli-stmt.bind-result.php, you use bind_result() to tell the statement what PHP variables to store results in, but you must fetch the results of the query as a separate call to fetch().

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Re comment: None of these functions return the result of your count.

The functions return TRUE on success, and FALSE on failure. They do not return the result of the query. That’s why you bind a variable, so the fetch can store the result in that variable as a side effect — not as a return value. You should not assign $count=*anything*.

Here’s how your code should look:

$stmt = $db->prepare("SELECT COUNT(id) FROM `users` WHERE `email`=? LIMIT 1") 
    or die($db->error);
$stmt->bind_param("s", $email) 
    or die ($stmt->error);
$stmt->execute() 
    or die ($stmt->error);
$stmt->bind_result($count)  // do not use return value
    or die ($stmt->error);
$stmt->fetch() // do not use return value
    or die ($stmt->error);
print ($count);
$stmt->close()
    or die ($stmt->error);
return ($count > 0 ? true : false);