$_SESSION variables "disappear" after form is submitted - php

Question

I stored values from a form in SESSION variables but it seems that they are emptied after if(isset($_POST['submit']) even though I can echo them earlier in my code. The code runs and the insert works except for $toto and $tata which are empty.
In the code below _id, master_label, client_label are inserted correctly. And the target table fields match so the error does not come from there.
<?php
session_start();
[...]
echo "<form id='organization' action='?' method='POST' enctype='multipart/form-data' >" ;
echo "<select name='organization' onchange='this.form.submit()'>"; //
echo '<option value="">Select ORGANIZATION</option>';
while ($row=mysqli_fetch_array($result00)) {
echo '<option value="'.$row['company_id'].'">'.$row['company_id'].'</option>';
}
echo "</select>";
echo "</form>";
$cie_ticker = $_POST['organization'] ;
$_SESSION['company_id'] = $cie_ticker ;
$sql="(SELECT company_id, databasefile, company_name FROM `settings` WHERE company_id='$cie_ticker') LIMIT 1";
$result=mysqli_query($connect,$sql) or die('Could not execute the query ' . mysqli_error()) ;
$data_bis=$result->fetch_array() ;
$_SESSION['selected_cie_id'] = $data_bis['company_id'];
$_SESSION['selected_cie_name'] = $data_bis['company_name'];
<form id='demoForm' action="?" method="POST" enctype="multipart/form-data" target="_top">
<?php
$file = fopen('./company/'.$cie_ticker.'/'.$_SESSION['selected_cie_db'], "r") ; // $file = fopen('./company/'.$_SESSION["company_id"].'/'.$_SESSION['selected_cie_db'], "r") ;
$headers=fgetcsv($file, 1000, "|");
fclose($file);
?>
<table id="user_table">
<tr><th>HEADERS </th><th>MASTER DB HEADERS</th></tr>
<?php foreach ($headers as $entete) {
$query01="SELECT master_label FROM `mastertable`";
$result01=mysqli_query($connect,$query01); ?>
<tr id="<?php echo $entete;?>">
<td> <?php echo $entete ?></td>
<td id="<?php echo $row['_id'];?>">
<?php
echo "<br>";
echo "<select name=".$entete.">";
echo '<option value="MASTER DATA">Select MASTER DATA</option>';
while ($row=mysqli_fetch_array($result01)) {
echo '<option value="'.$row['master_label'].'">'.$row['master_label'].'</option>';
}
echo "</select>";
?>
</td>
</tr>
<?php } ?>
</table>
<input id="checkBtn" type="submit" name="submitbutton" value="SAVE" class="button"/>
</form>
if(isset($_POST['submitbutton'])) {
$toto = $data_bis['company_id'] ;
$tata = $data_bis['company_name'];
$selected=$_POST;
foreach($selected as $x => $x_value) {
$query= $connect->prepare("INSERT INTO `mytable` (_id, master_label, client_label, org_label, client_id) VALUES ('',?,?,?,?) ");
$query->bind_param('ssss',$x_value, $x, $toto, $tata );
$query->execute();
}
}
?>

Answer 1

I have found the answer:
In this case one must add hidden input for the $_SESSION variables otherwise they were lost after submitting the form.