如何在PHP中修复“ mysqli_num_rows（）期望参数1为mysqli_result，给定布尔值”

Question

此代码输出：“ mysqli_num_rows（）期望参数1为mysqli_result，给定布尔值”，我试图在此网站上找到相同的情况，但找不到解决我问题的解决方案。

<?php
session_start();

$con = mysqli_connect('localhost','root','T07iSHxIblmIMc0c');

mysqli_select_db($con, 'login');

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

$s = "SELECT * FROM users where name= '$name' && password = '$pass'";

$result = mysqli_query($con, $s);
$num = mysqli_num_rows($result);

if($num == 1){
    header('location:statistics.php');
}else{
    header('location:login.php');
}


?>