I am unable to view the database

<?php 

include("inc/functions.php");


if (isset($_GET["id"])) {
    $id = 
        filter_input(INPUT_GET,"id",FILTER_SANITIZE_NUMBER_INT); //Sanitizing Input
        $item = single_item_array($id);
}

if (empty($item)) {
    header("location:catalog.php");
    exit;
}

$pageTitle = $item["title"];
$section = null;

include("inc/header.php"); ?>

<div class="section page">

    <div class="wrapper">

        <div class="breadcrumbs">
            <a href="catalog.php">Full Catalog</a>
            &gt; <a href="catalog.php?cat=<?php echo strtolower($item["category"]); ?>">
            <?php echo $item["category"]; ?></a>
            &gt; <?php echo $item["title"]; ?>
        </div>

        <div class="media-picture">

        <span>
            <img src="<?php echo $item["img"]; ?>" alt="<?php echo $item["title"]; ?>" />
        </span>

        </div>

        <div class="media-details">

            <h1><?php echo $item["title"]; ?></h1>
            <table>

                <tr>
                    <th>Category</th>
                    <td><?php echo $item["category"]; ?></td>
                </tr>
                <tr>
                    <th>Genre</th>
                    <td><?php echo $item["genre"]; ?></td>
                </tr>
                <tr>
                    <th>Format</th>
                    <td><?php echo $item["format"]; ?></td>
                </tr>
                <tr>
                    <th>Year</th>
                    <td><?php echo $item["year"]; ?></td>
                </tr>
                <?php if (strtolower($item["category"]) == "books") { ?>
                <tr>
                    <th>Authors</th>
                    <td><?php echo implode(", ",$item["author"]); ?></td>
                </tr>
                <tr>
                    <th>Publisher</th>
                    <td><?php echo $item["publisher"]; ?></td>
                </tr>
                <tr>
                    <th>ISBN</th>
                    <td><?php echo $item["isbn"]; ?></td>
                </tr>    
                <?php } else if (strtolower($item["category"]) == "movies") { ?>
                <tr>
                    <th>Director</th>
                    <td><?php echo  implode(", ", $item["director"]) ;?></td>
                </tr>
                <tr>
                    <th>Writers</th>
                    <td><?php echo implode(", ",$item["writer"]); ?></td>
                </tr>
                <tr>
                    <th>Stars</th>
                    <td><?php echo implode(", ",$item["star"]); ?></td>
                </tr>
                <?php } else if (strtolower($item["category"]) == "music") { ?>
                <tr>
                    <th>Artist</th>
                    <td><?php echo  implode(", ",$item["artist"]); ?></td>
                </tr>
                <?php } ?>
            </table>

        </div>

    </div>

</div>

<?php

function full_catalog_array(){
    include("connection.php");
        try {
        $result=$db->query("SELECT media_id, title, category, img FROM Media");
        //echo "Retrieved the results";
    } catch (Exception $e) {
        echo "Bad query";
    }
        $catalog=$result->fetchAll();
        return $catalog;
    }

function single_item_array($id){
    include("connection.php");
        try {
        $result=$db->prepare("
        SELECT Media.media_id, title, category, img, format, year, genre ,publisher, isbn FROM Media
        JOIN Genres on Media.genre_id=Genres.genre_id
        LEFT OUTER JOIN  Books on Media.media_id=Books.media_id
        WHERE Media.media_id = ?
        ");
        $result->bindParam(1,$id,PDO::PARAM_INT);
        $result->execute(); 
    } catch (Exception $e) {
        echo "Bad query";
            exit;
    }
        $item=$result->fetch();//Since we want to take only one item
        if(empty($item)) return $item;
                try {
        $result=$db->prepare("
        SELECT fullname, role
        FROM Media_People
        JOIN People on Media_People.people_id=People.people_id
        WHERE Media_People.media_id = ?
        ");
        $result->bindParam(1,$id,PDO::PARAM_INT);
        $result->execute(); 
    } catch (Exception $e) {
        echo "Bad query";
            exit;
    }
        while($row=$result->fetch(PDO:FETCH_ASSOC)){
            $item[$row["role"]][]=$row["fullname"];
        }
        return $item;
    }
function get_item_html($id,$item) {
    $output = "<li><a href='details.php?id="
        . $item["media_id"] . "'><img src='" 
        . $item["img"] . "' alt='" 
        . $item["title"] . "' />" 
        . "<p>View Details</p>"
        . "</a></li>";
    return $output;
}

function array_category($catalog,$category) {
    $output = array();

    foreach ($catalog as $id => $item) {
        if ($category == null OR strtolower($category) == strtolower($item["category"])) {
            $sort = $item["title"];
            $sort = ltrim($sort,"The ");
            $sort = ltrim($sort,"A ");
            $sort = ltrim($sort,"An ");
            $output[$id] = $sort;            
        }
    }

    asort($output);
    return array_keys($output);
}```