Php 我收到这个信息，为什么？mysqli_query（）：无法获取mysqli

这是连接页面，它与我的索引文件配合得很好。现在的问题是：我需要在另一个页面上运行另一个sql，它应该是这样运行的：SELECT*FROM products，其中id=$var。但是它给了我mysqli\u查询：当我尝试获取mysqli时，我应该怎么做

connection.php

$host = "localhost";
$dbusername = "root";
$dbpassword = "";
$db = "movies";

//connecting to the database
$conn = mysqli_connect("$host","$dbusername","$dbpassword","$db");
mysqli_set_charset($conn,'utf8');

//check for error in connection
if (!$conn) {
  die ('Failed to connect to MySQL: ' . mysqli_connect_error());
}

//Selecting table and executing query
$sql = 'SELECT * FROM products';
$query = mysqli_query($conn, $sql);

if (!$query) {
  die ('SQL Error: ' . mysqli_error($conn));
}

mysqli_close($conn);

-另一页-

<?php

include "connection.php";

$movieid = $_GET['movieid'];

$sql = 'SELECT * FROM products WHERE id = "$movieid"';
$query = mysqli_query($conn, $sql);

$movie_title = $row['title'];
echo "$movie_title";
?>

---

此错误的原因是您正在关闭connenction.php文件上的连接。您只需删除此行：

mysqli_close($conn);