function getHtmlTable($rs){
// receive a record set and print
// it into an html table
$out = '<table>';
while ($field = $rs->fetch_field()) $out .= "<th>".$field->name."</th>";
while ($linea = $rs->fetch_assoc()) {
$out .= "<tr>";
foreach ($linea as $valor_col) $out .= '<td>'.$valor_col.'</td>';
$out .= "</tr>";
}
$out .= "</table>";
return $out;
}