<input type="submit" value="Enviar"/>...

<form action="bd.php" method="post" enctype="multipart/form-data">
 <input type="text" name="texto">
 <input type="submit" value="Enviar"/>
</form>

<?php
$sql = "INSERT INTO `table` (`TEXTO`) VALUES ('{$_POST['texto']}')";
header("Location: sair.php");