$salida = "";
$query = "SELECT * FROM productos ORDER By ID";
$cantidad = 0;

//$Unidad = $fila['ProductU'];

if(isset($_POST['e']) && isset($_POST['c'])){
    $q = $conexion->real_escape_string($_POST['e']);
    $query = "SELECT ID, ProductN, ProductP, ProductU, ProductS FROM productos WHERE ID LIKE '%".$q."%'";
    $cantidad = $_POST['c'];
}

$resultado = $conexion->query($query);
$salida.="<table class='table table-sm' id='tabla' autofocus>
                <thead class='thead-light'>
                    <tr>
                           <th scope='col'>Cantidad</th>
                        <th scope='col'>Unid.</th>
                        <th  scope='col'>ARTICULO</th>
                        <th  scope='col'>P. Unitario</th>
                        <th>TOTAL</th>
                    </tr>
                </thead>
                <tbody>";
$fila = $resultado->fetch_assoc();
              $salida.="<tr>
                    <td>".$cantidad."</td>
                    <td>".$fila['ProductU']."</td>
                    <td>".$fila['ProductN']."</td>
                    <td>".$fila['ProductP']."</td>
                    <td>40</td>
                 </tr>";
//if($resultado->num_rows > 0){
  //  $i
    //for($i=1; $i<4; $i++){
    //  echo "hola";
    //}
    //while($fila = $resultado->fetch_assoc()){


    //}

    $salida.="</tbody</table>";


 echo $salida;
$conexion->close();

?>