我的 PHP 函数中有哪些问题导致发生致命错误？

Question

getUserIDForEmail 应该查询 MySQL 数据库并搜索电子邮件地址并获取相应的用户 ID。

这个测试用例：

$adminId = getUserIDForEmail("a.h@outlook.com");

导致此错误：

Fatal error: Uncaught Error: Call to a member function execute() on boolean in /.../public_html/db.php:51 Stack trace: #0 /.../public_html/register.php(5): getUserIDForEmail('a.h@outlook.com') #1 {main} thrown in /.../public_html/db.php on line 51

第 51 行是：

$stmt = $stmt->execute();

来自这段代码：

/* code omitted here */

$conn = new mysqli(DB['servername'], DB['username'], DB['password'], DB['dbname']);

if ($conn->connect_error) {
    die('Connection failed: ' . $conn->connect_error);
}

session_start();

/* code omitted here */

/**
 * Query database for registered email and get user ID.
 * 
 * @param {String} $email
 * @return {Number} $userID
 */
function getUserIDForEmail($email) {

    global $conn;

    $userID = -1;
    $sql = '';
    $stmt = null;
    $row = null;

    if (empty($email)) {
        throw new Exception("Email is undefined");
    } else if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        throw new Exception("Email is not correctly formatted");
    }

    $sql = "SELECT `id` FROM `UserAccount` WHERE `email` = ?";

    /* Avoid SQL injection */
    if ($stmt = $conn->prepare($sql)) {
        $stmt = $stmt->bind_param('s', $email);
        $stmt = $stmt->execute();

        if ($stmt->num_rows > 0) {
            $row = $result->fetch_assoc(); // first result
            $userID = $row["id"];
        }

        $stmt->close();
    }

    return $userID;
}

Answer 1

bind_param() returns a boolean 并且您正在将其重新分配给 $stmt。您正在对 execute() 做同样的事情。只需调用 $stmt 对象上的方法：

$stmt->bind_param('s', $email);
$stmt->execute();

那么你会遇到问题，因为没有 $result:

$row = $result->fetch_assoc();

所以只需 fetch() 来自语句：

$row = $stmt->fetch(PDO::FETCH_ASSOC);

Answer 2

mysqli_stmt::bind_param returns 布尔值： http://php.net/manual/en/mysqli-stmt.bind-param.php

只需从#50 行删除“$stmt =”即可。

我的 PHP 函数中有哪些问题导致发生致命错误？

What are the issues in my PHP function that are causing a fatal error to occur?

php

mysql

mysqli

boolean

execute