<?php
error_reporting(-1);
ini_set('display_errors', 1);
header('Content-Type: text/html; charset=utf-8');
session_start();

include_once "var.php";
$link = mysqli_connect($dbhost, $dbuser, $dbpass, $dbname) or exit(mysqli_error());
mysqli_set_charset($link, 'utf8');

##########
if (isset($_GET['id']) && $_GET['id'] == int($_GET['id'])) {
    $news = mysqli_query($link, "SELECT * FROM `news` WHERE `id`=" . int($_GET['id']) . "");
    if (mysqli_num_rows($news)) {
        while ($row = mysqli_fetch_assoc($news)) {
            echo $row['textfull'] . '<hr><br>FULL ST';
        }
    } else {
        echo "нет ноалсти с таким id";
    }
} elseif (isset($_GET['cat']) && $_GET['cat'] == int($_GET['cat_id'])) {
    $res = mysqli_query($link, "SELECT * FROM `news` WHERE `cat_id`=" . int($_GET['cat_id']) . "");
    if (mysqli_num_rows($res)) {
        while ($row = mysqli_fetch_assoc($res)) {
            echo $row['title'] . "<hr>";
        }
    }
} else {
    //
    $news = mysqli_query($link, "SELECT * FROM `news` ORDER BY `id` DESC");
    if (mysqli_num_rows($news)) {
        echo '<a href=index.php>main page</a><br><br>Всего новостей: (' . mysqli_num_rows($news) . ') <hr><br>';
        while ($row = mysqli_fetch_assoc($news)) {
            echo '<div>' . $row['title'] . ' </div><div><i>' . $row['name'] . '</i></div><div><a href=\'?cat=' . $row['cat_id'] . '\'><b>' . $row['cat_id'] . '</b></a></div><div>' . $row['textshort'] . '</div><div>' . $row['textfull'] . '</div><div><small>' . $row['date'] . '</small></div><hr><br>';
        }
    } else {
        echo 'Записей нет';
    }
}

?>