大佬们，这该怎么办

Question

<?php

session_start();

header("Content-type:text/html;charset=utf-8");    //设置编码

$page=isset($_GET['page']) ?$_GET['page'] :1 ;//接收页码

$page=!empty($page) ? $page :1;

$F=$_GET['F'];

// 创建连接

$conn = mysqli_connect("localhost", "root", "", "mybbs");

mysqli_set_charset($conn,'utf8'); //设定字符集

$table_name="tiopic";//查取表名设置

$perpage=5;//每页显示的数据个数

//最大页数和总记录数

$total_sql="select count(*) from $table_name";

$total_result =mysqli_query($conn,$total_sql);

$total_row=mysqli_fetch_row($total_result);

$total = $total_row[0];//获取最大页码数

$total_page = ceil($total/$perpage);//向上整数

//临界点

$page=$page>$total_page ? $total_page:$page;//当下一页数大于最大页数时的情况

//分页设置初始化

$start=($page-1)*$perpage;

$sql="select * from tiopic order by id desc limit $start ,$perpage";

$query=mysqli_query($conn,$sql);

$sum=mysqli_num_rows($query);

?>