CRUD actores Sakila

Index.php

     <h1>Mantenimiento actores de Sakila</h1>
        <form>
            <input type="hidden" name="action" value="insert">
            Nombre:<input type="text" name="first_name">
            Apellidos:<input type="text" name="last_name">
            <input type="submit" class="btn btn-info">
        </form>
        <table class="table">
            <tr><td>Id</td><td>Nombre</td><td>Apellidos</td><td>Acciones</td></tr>
            <?php
            $server = "localhost";
            $user = "root";
            $password = "";
            $db = "sakila";
            $action = filter_input(INPUT_GET, 'action');
            $last_name = filter_input(INPUT_GET, 'last_name', FILTER_SANITIZE_STRING);
            $first_name = filter_input(INPUT_GET, 'first_name', FILTER_SANITIZE_STRING);
            $actor_id = filter_input(INPUT_GET, 'actor_id', FILTER_VALIDATE_INT);
            try {
                $conn = new PDO("mysql:host=$server;dbname=$db", $user, $password);
                $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

                //Acciones sobre la base de datos
                if ($action == 'insert' && !empty($first_name) && !empty($last_name)) {
                    $sql = "insert into actor (first_name, last_name) values ('$first_name','$last_name')";
                    $conn->exec($sql);
                }
                if ($action == "delete" && !empty($actor_id)) {
                    $sql = "delete from actor where actor_id=$actor_id";
                    $conn->exec($sql);
                }
                if ($action == 'update' && !empty($first_name) && !empty($last_name) && !empty($actor_id)) {
                    $sql = "update actor set first_name='$first_name', last_name='$last_name' where actor_id=$actor_id";
                    $conn->exec($sql);
                }

                $sql = "select * from actor";
                $resul = $conn->query($sql);
                while ($fila = $resul->fetch(PDO::FETCH_ASSOC)) {
                    ?>
                    <tr><td><?= $fila['actor_id'] ?></td>
                        <td><?= $fila['first_name'] ?></td>
                        <td><?= $fila['last_name'] ?></td>
                        <td><a href="?action=delete&actor_id=<?= $fila['actor_id'] ?>">Borrar</a>
                            <a href="update.php?actor_id=<?= $fila['actor_id'] ?>">Editar</a></td></tr>

                    <?php
                }
            } catch (Exception $ex) {
                echo "Ha ocurrido un error<br/>" . $ex->getMessage();
            }
            ?></table>

update.php

  <h1>Editar actor</h1>
        <?php
        $server = "localhost";
        $user = "root";
        $password = "";
        $db = "sakila";
        $actor_id = filter_input(INPUT_GET, 'actor_id', FILTER_VALIDATE_INT);
        if (!empty($actor_id)) {
            try {
                $conn = new PDO("mysql:host=$server;dbname=$db", $user, $password);
                $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
                $sql = "select * from actor where actor_id=$actor_id";
                $resul=$conn->query($sql);
                $fila=$resul->fetch();
            } catch (Exception $ex) {
                echo "Ha ocurrido un error<br/>" . $ex->getMessage();
            }
        }
        ?>
        <form action="index.php">
             <input type="hidden" name="action" value="update">
             <input type="hidden" name="actor_id" value="<?=$actor_id?>">
            Nombre:<input type="text" name="first_name" value="<?=$fila['first_name']?>">
            Apellidos:<input type="text" name="last_name" value="<?=$fila['last_name']?>">
            <input type="submit" class="btn btn-info">
        </form>

final.php

 <h1>Consulta actores de Sakila</h1>
        <form>
            Nombre:<input type="text" name="first_name">
            Apellidos:<input type="text" name="last_name">
            <input type="submit" class="btn btn-info" value="Buscar">
        </form>
        <table class="table">
            <tr><td>Id</td><td>Nombre</td><td>Apellidos</td></tr>
            <?php
            $server = "localhost";
            $user = "root";
            $password = "";
            $db = "sakila";
            $last_name = filter_input(INPUT_GET, 'last_name', FILTER_SANITIZE_STRING);
            $first_name = filter_input(INPUT_GET, 'first_name', FILTER_SANITIZE_STRING);
            try {
                $conn = new PDO("mysql:host=$server;dbname=$db", $user, $password);
                $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);


                $sql = "select * from actor where 1";
                if (!empty($first_name)){
                    $sql.=" and first_name like '%$first_name%'";
                }
                if (!empty($last_name)){
                    $sql.=" and last_name like '%$last_name%'";
                }
                $resul = $conn->query($sql);
                while ($fila = $resul->fetch(PDO::FETCH_ASSOC)) {
                    ?>
                    <tr><td><?= $fila['actor_id'] ?></td>
                        <td><?= $fila['first_name'] ?></td>
                        <td><?= $fila['last_name'] ?></td>
                    </tr>

                    <?php
                }
            } catch (Exception $ex) {
                echo "Ha ocurrido un error<br/>" . $ex->getMessage();
            }
            ?></table>