Linux, Apache, MySQL, PHP

Please how can I use $_SERVER['PHP_SELF'] code to save record and print 
simultaneouly using PHP. I need the data been submitted into the database to print on the POS printer. See form action used below. Please assist. 

<form method="post" name="form1" action="<?php echo $editFormAction; ?> target="_parent">

php $_SERVER['PHP_SELF']

<input type= button name="Print receipt" onClick=window.open("print_process_script.php","width=550,height=300,left=150,top=200,toolbar=0,") value="Print Reciept" />

$query = "Select Max(Serial_Number) From captain_order";
	$returnD = mysql_query($query);
	$result = mysql_fetch_assoc($returnD);
	Print mysql_error();
	$maxRows = $result['Max(Serial_Number)'];
  if(empty($maxRows)){
	    $lastRow = $maxRows = 1;       
    }else{
		$lastRow = $maxRows + 0001 ;
    }

How to use PHP global processing script action to process sumbitted data and display form data entered on the text on another page

Please I need a guide on how to use a php $_SERVER['PHP_SELF'] to insert form data into Mysql database and redisplay data entered on another form. 

My form action is <pre><form method="post" name="form1" action="<?php echo $editFormAction; ?>

<input name="Print receipt" type= "button" onclick = "Openform();" value="Print reciept" /></td>

$res = $conn->query("SELECT * FROM `users` WHERE `email`= '$email'");

if (mysqli_num_rows($res) != 0) {
  echo "<br>  Sorry this email already is registered with us!!!  <br>";
  $start = microtime(true);
  do {
    $stop = microtime(true);
  } while ($stop - $start < 5);
  header("location: index.php");
}
else {
  // Password hashing
  $cost = 8;
  $target_time = 0.05;
  // When microtime is set to true it returns a float
  // If set to false then returns a string

  do {
    $start = microtime(true);
    $password = password_hash( $password, PASSWORD_BCRYPT, ["cost" => $cost] );
    $stop = microtime(true);
    $cost++;

  } while ($stop - $start < $target_time);


  $date = date("Y-m-d ");

  $sql="INSERT INTO `users` (`username`, `email`, `password`, `sign_up_date`)
  VALUES ('$username', '$email', '$password', '$date')";

  if ($conn->query($sql)) {
    echo "Registration Successful!!!";
    header( "location: index.php" );
  }

}

$conn = new mysqli( "localhost", $user, $pass, $db ) or die("Unable to connect");

$email = mysqli_real_escape_string($conn, $_POST['email']);

$res = $conn->query("SELECT * FROM `users` WHERE `email`= '$email'");

if (mysqli_num_rows($res) == false) {
  echo "Sorry no such user exists :(";
}
else {
  $user = $res->fetch_assoc();

  if ( password_verify(  $_POST['password'], $user['password']) ) {
    echo " Password login accepted. Redirecting...";
    $_SESSION['username'] = $user['username'];
    $_SESSION['email'] = $user['email'];

    $_SESSION['logged_in'] = true;
    header("location: testFront.php");
  }
  else {
    echo "<br>Sorry Wrong Password!!!<br>";
  }

}

<pre><table>
            <tr>
                <!--Mostramos el titulo de la encuesta-->
                <td colspan="2"> <h3><?php echo $titulo; ?></h3></td>
            <input type="hidden" name="id" value="<?php echo $id; ?>">
            </tr>
            <?php
            //consulta que captura el texto , id de la tabla respuestas
            $sql = "SELECT texto,id FROM respuestas WHERE idenc='$id'";
            $sql = mysqli_query($conexion,$sql);
            //ahora recorremos los datos texto, id que estan vinculadas a la cuenta seleccionada
            while ($row = mysqli_fetch_array($sql)){
                $texto = $row["texto"];
                $idres = $row["id"];
                 
            ?>
            
        
            <tr>
              <!--  <td width="50"><input type="radio" name="opcion" value="<?php echo $idres; ?>" required</td>
                <td width="470"><?php echo $texto; ?></td>-->
                <td width="50"><?php echo $idres; ?></td>
                <td width="470"><?php echo $texto; ?></td>
                <td> SI <input type="radio" name="radio<?php echo $idres; ?>" value="SI"></td>
                <td> NO <input type="radio" name="radio<?php echo $idres; ?>" value="NO"></td>
                <td><textarea name="comentarios<?php echo $idres; ?>" rows="5" cols="20">Escribe aquí tus Hallazgos</textarea></td>
                <td><textarea name="acciones<?php echo $idres; ?>" rows="5" cols="20">Escribe aquí tus Acciones Correctivas</textarea></td>
            </tr>
            <?php } ?>

<pre><?php
/*$opcion = $_POST["opcion"];*/
$respuesta = $_POST["radio$idres"];
$comentarios = $_POST["comentarios$idres"];
$acciones = $_POST["acciones$idres"];
require 'conexion.php';

//obtenemos la fecha del sistema
$fecha_actual = date("y-m-d");

//obtenemos el numero actual de votos para la opcion elegir
//comprovamos si $opcion no esta vacio
if(!empty($respuesta)){
    $sql = "INSERT INTO opciones(ID, idenc, valor, Accion, hallazgo, fecha) VALUES ('$respuesta' ,'$comentarios' ,'$acciones' ,'$fecha_actual')";
    $sql = mysqli_query($conexion,$sql);
}
header("Location: verEncuesta.php");
?>

<!DOCTYPE html>
<html >
<head>
	<style type="text/css">
	.centerDiv
	{
		width: 1000px;
		height:600px;
		margin: 0 auto;
	}
	.div1
	{
		width: 500px;
		height:600px;
		float:left;
	}
	.div2
	{
		width: 500px;
		height:600px;
		float:left;
	}
	</style>
</head>
<body>
	<div class="centerDiv">
		<div class="div1">
		<object type="text/html" data="https://Somewebsite.com" width="500px" height="600px" style="inline-block:auto;border:5px ridge blue">
    </object>
		</div>
		<div class="div2">
		<object type="text/html" data="https://Somewebsite.com" width="500px" height="600px" style="inline-block:auto;border:5px ridge blue">
    </object>
		</div>
	</div>
</body>
</html>