How to write in session selected value in select?

Question

PHP

Forming a list

<select id="sel_">
    <?php
      $query_= "SELECT * FROM category_information";
      $sql_q=mysql_query($query_);
          
      while ($row = mysql_fetch_row($sql_q))
        {
          echo '<option name="op_cat_id" value="'.$row[0].'">'.$row[1].'</option>';
        }

        
    ?>
</select>

How, when selecting the "op_cat_id" element, write "value" to the session?

Answer 1

How, when selecting the "op_cat_id" element, write "value" to the session?

The choice occurs in the browser, and you can write to the session on the server.
Means it is necessary to transfer event from the browser to the server. For example, through AJAX.

Answer 2

Look for the selected element not by the option name, but by the name or identifier select
For example, by attaching a script to the select:
$('#sel_').change(function(){
var id = $(this).val();
// and then you push the value into the session with Ajax
});

Answer 3

It is possible through cookies: <?
// send cookie
setcookie("cookie[select]", $row[0]);
// after page reload, output cookie
if (isset($_COOKIE['cookie'])) {
foreach ($_COOKIE['cookie'] as $name => $value) {
$name = htmlspecialchars($name);
$value = htmlspecialchars($value);
echo "$name : $value
\n";
}
}
?>