我有一个工作INSERT语句，允许访问者在我的网站上创建一个帐户。
我正在尝试创建一个SELECT语句来检查他们正在尝试注册的用户名是否当前存在。由于某种原因，在运行SELECT语句时，我在INSERT语句(第29行)上得到了一个Call to a member function bind_param() on boolean。
为什么会这样?我已经提供了我的代码…
<?php
require '../manager-session.php';
require '../../db-config.php';
require '../../distributor-config.php';
$role = 'User';
$title = $_POST['title'];
$firstname = $_POST['firstname'];
$surname = $_POST['surname'];
$company = $_SESSION['userinfo']['company'];
$emailaddress = $_POST['emailaddress'];
$telephone = $_POST['telephone'];
$addressline1 = $_POST['addressline1'];
$addressline2 = $_POST['addressline2'];
$addressline3 = $_POST['addressline3'];
$towncity = $_POST['towncity'];
$county = $_POST['county'];
$postcode = $_POST['postcode'];
$username = $_POST['username'];
$password = $_POST['password'];
$stmt_check = "SELECT username FROM users WHERE username = ?";
$stmt_check = $conn->prepare($stmt_check);
$stmt_check->bind_param('s', $_POST['username']);
$stmt_check->execute();
if($stmt_check == true) {
$stmt = $conn->prepare("INSERT INTO users (role, distributor, company, title, firstname, surname, emailaddress, telephone, addressline1, addressline2, addressline3, towncity, county, postcode, username, password) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)");
$stmt->bind_param("ssssssssssssssss", $role, $distributor, $company, $title, $firstname, $surname, $emailaddress, $telephone, $addressline1, $addressline2, $addressline3, $towncity, $county, $postcode, $username, $password);
$stmt->execute();
$to = "". $emailaddress ."";
$subject = "New User Account";
$txt = "". $firstname ." ". $surname ." has created a new User account for ". $distributor .". Please login using the following details:'n'nUsername: ". $username ."'nPassword: ". $password ."";
$headers = "From: removed@email.com" . "'r'n" . "BCC: removed@email.com, removed@email.com ". $distributoremail ."";
mail($to, $subject, $txt, $headers);
header('location: ../add-a-new-user.php?page=add-a-new-user&status=success');
exit();
}
else {
header('location: ../add-a-new-user.php?page=add-a-new-user&status=error');
exit();
}
$stmt->close();
$conn->close();
?>
mysqli->prepare在预处理语句失败时返回false。这可能是由于SQL语法错误或其他SQL错误。
编辑:很明显，您可以得到如下所示的预处理语句错误:
$stmt = $conn->stmt_init();
$stmt->prepare("...");
var_dump($stmt->error);