mysqli\u real\u escape\u string（）功能不正常

Question

我有以下PHP函数：

public function signup() {
        $mysql = mysqli_connect(HOSTNAME, USERNAME, PASSWORD, DATABASE);
        if (mysqli_connect_errno($mysql)) {
            $this->viewModel->set("pageTitle", "Signup");
            $this->viewModel->set("message", "There was an error connecting to the server.");
            return $this->viewModel;
        }
        if ($result = $mysql->query("SELECT id FROM mailinglist WHERE email='" . $this->email . "';")) {
            if ($result->num_rows == 0) {
                $mysql->query("INSERT INTO mailinglist (email) VALUES ('" . $this->email . "');");
                $this->viewModel->set("message", "Great! Thanks for signing up " . $this->email . ".");
            } else {
                $this->viewModel->set("message", "You are already signed up for updates!");
            }
        } else {
            $this->viewModel->set("message", "There was an error adding you the mailing list.");
        }
        $this->viewModel->set("pageTitle", "Signup");
        return $this->viewModel;
    }

它运行良好，并返回我想要的，但是，如果我试图使用mysqli_real_escape_string（）来查询，它就不起作用。也就是下面的代码

public function signup() {
        $mysql = mysqli_connect(HOSTNAME, USERNAME, PASSWORD, DATABASE);
        if (mysqli_connect_errno($mysql)) {
            $this->viewModel->set("pageTitle", "Signup");
            $this->viewModel->set("message", "There was an error connecting to the server.");
            return $this->viewModel;
        }
        $query = $mysql->real_escape_string("SELECT id FROM mailinglist WHERE email='" . $this->email . "';");
        if ($result = $mysql->query($query)) {
            if ($result->num_rows == 0) {
                $query = $mysql->real_escape_string("INSERT INTO mailinglist (email) VALUES ('" . $this->email . "');");
                $mysql->query($query);
                $this->viewModel->set("message", "Great! Thanks for signing up " . $this->email . ".");
            } else {
                $this->viewModel->set("message", "You are already signed up for updates!");
            }
        } else {
            $this->viewModel->set("message", "There was an error adding you the mailing list.");
        }
        $this->viewModel->set("pageTitle", "Signup");
        return $this->viewModel;
    }

不起作用。连接没有问题，我尝试使用mysqli\u real\u escape\u string（）而不是$mysql-

Answer 1

您必须转义数据，而不是整个查询。

public function signup() {
        $mysql = mysqli_connect(HOSTNAME, USERNAME, PASSWORD, DATABASE);
        if (mysqli_connect_errno($mysql)) {
            $this->viewModel->set("pageTitle", "Signup");
            $this->viewModel->set("message", "There was an error connecting to the server.");
            return $this->viewModel;
        }
       $query = "SELECT id FROM mailinglist WHERE email='" .$mysql->real_escape_string( $this->email ). "'"
        if ($result = $mysql->query($query)) {
            if ($result->num_rows == 0) {
               $query = "INSERT INTO mailinglist (email) VALUES ('" . $mysql->real_escape_string($this->email) . "')";
                $mysql->query($query);
                $this->viewModel->set("message", "Great! Thanks for signing up " . $this->email . ".");
            } else {
                $this->viewModel->set("message", "You are already signed up for updates!");
            }
        } else {
            $this->viewModel->set("message", "There was an error adding you the mailing list.");
        }
        $this->viewModel->set("pageTitle", "Signup");
        return $this->viewModel;
    }

Answer 2

不要这样做，使用准备好的语句。它们更安全、更可靠。您仍然需要清理数据以获得适当的值和跨站点脚本，列举一些您仍然会遇到的风险。逃避数据是防止SQL注入的一种方法，但这并不是充分的证据。准备好的语句告诉数据库服务器假设传入的数据是不安全的，只是接受它，而不是像串联字符串一样处理它。数据库将参数视为语句的变量，而不是语句的一部分。

以下是您如何将自己的声明更改为准备好的声明：

$stmt=$mysql->prepare("SELECT id FROM mailinglist WHERE email=?");
$stmt->bind_param('s',$this->email);
$result=$stmt->execute();
if ($result) {
    if ($result->num_rows == 0) {
        $stmt=$mysql->prepare("INSERT INTO mailinglist (email) VALUES (?)");
        $stmt->bind_param('s', $this->email);
        $stmt->execute();
        $this->viewModel->set("message", "Great! Thanks for signing up " . $this->email . ".");
     } else {
        $this->viewModel->set("message", "You are already signed up for updates!");
     }
} else {
     $this->viewModel->set("message", "There was an error adding you the mailing list.");

}