How to get file from inside the database?

Question

I’m using postgresql as sgdb, and I’m saving files. txt in bd, so far, all right, it’s working right, but I’m not finding a way to get the content of the txt files saved in bd, I’m using php with PDO for connection to bd

The type of column that saves txt in the database is OID, which stores a wide_object

I am saving the txt file in the database like this:

session_start();
require 'database.php';

$n_documento    = (!empty($_POST['documento']))     ? $_POST['documento']       : '';
$n_capitulo     = (!empty($_POST['capitulo']))      ? $_POST['capitulo']        : '';
$titulo         = isset($_POST['titulo'])           ? $_POST['titulo']          : '';
$paragrafo      = isset($_POST['valor_paragrafo'])  ? $_POST['valor_paragrafo'] : '';

$fp = fopen("capitulo_$n_capitulo.txt", "w+");
$conteudo = fwrite($fp, $paragrafo);
fclose($fp);
if(!empty($_POST)) {
    $pdo = Database::connect();
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $sql = "UPDATE capitulos SET
                paragrafo = lo_import('C:/wamp/www/crud/capitulo_$n_capitulo.txt'),
                titulo = $titulo
            WHERE id_documento = $n_documento
                  AND n_capitulo = $n_capitulo";
    $pdo->query($sql);
    Database::disconnect();
}

how do I get this txt I saved? whatever the shape, either by sql or by php.