Simple implementation of php paging code_PHP tutorial

<?php
// 数据库连接常量
define(&#39;DB_HOST&#39;, &#39;localhost&#39;);
define(&#39;DB_USER&#39;, &#39;root&#39;);
define(&#39;DB_PWD&#39;, &#39;&#39;);
define(&#39;DB_NAME&#39;, &#39;guest&#39;);

// 连接数据库
function conn()
{
    $conn = mysqli_connect(DB_HOST, DB_USER, DB_PWD, DB_NAME);
    mysqli_query($conn, "set names utf8");
    return $conn;
}

//获得结果集
function doresult($sql){
   $result=mysqli_query(conn(), $sql);
   return  $result;
}

//结果集转为对象集合
function dolists($result){
    return mysqli_fetch_array($result, MYSQL_ASSOC);
}

function totalnums($sql) {
    $result=mysqli_query(conn(), $sql);
    return $result->num_rows;
}




// 关闭数据库
function closedb()
{
    if (! mysqli_close()) {
        exit(&#39;关闭异常&#39;);
    }
}

?>

<?php
include &#39;mysqli.func.php&#39;;

// 总记录数
$sql = "SELECT dg_id  FROM  tb_user ";
$totalnums = totalnums($sql);

// 每页显示条数
$fnum = 8;

// 翻页数
$pagenum = ceil($totalnums / $fnum);

// 页数常量
@$tmp = $_GET[&#39;page&#39;];

//防止恶意翻页
if ($tmp > $pagenum)
    echo "<script>window.location.href=&#39;index.php&#39;</script>";

//计算分页起始值
if ($tmp == "") {
    $num = 0;
} else {
    $num = ($tmp - 1) * $fnum;
}

// 查询语句
$sql = "SELECT dg_id,dg_username  FROM  tb_user ORDER BY dg_id DESC LIMIT " . $num . ",$fnum";
$result = doresult($sql);

// 遍历输出
while (! ! $rows = dolists($result)) {
    echo $rows[&#39;dg_id&#39;] . " " . $rows[&#39;dg_username&#39;] . "<br>";
}

// 翻页链接
for ($i = 0; $i < $pagenum; $i ++) {
    echo "" . ($i + 1) . "";
}
?>