I use an adaptation of this plugin jQuery Seat Chart

Here it is some lines:

1.    click: function () { //Click event
         if (this.status() == 'available') { //optional seat
          var maxSeats = 3;
          var ms = sc.find('selected').length;
          //alert(ms);
          if (ms < maxSeats) {
          
           price = this.settings.data.price;
          
      
            
         $('<option selected>R'+(this.settings.row+1)+' S'+this.settings.label+'</option>')
            .attr('id', 'cart-item-'+this.settings.id)
            .attr('value', this.settings.id)
            .attr('alt', price)
            .data('seatId', this.settings.id)
            .appendTo($cart);
      
           $counter.text(sc.find('selected').length+1);
           $counter.attr('value', sc.find('selected').length+1);
      
           $total.text(recalculateTotal(sc));
           $total.attr('value', recalculateTotal(sc));
      
           return 'selected';
          }
           alert('You can only choose '+ maxSeats + ' seats.');
           return 'available';
      
         } else if (this.status() == 'selected') { //Checked
      
           //Update Number
           $counter.text(sc.find('selected').length-1);
           $counter.attr('value', sc.find('selected').length-1);
      
           //Delete reservation
           $('#cart-item-'+this.settings.id).remove();
      
           //update totalnum
           $total.text(recalculateTotal(sc));
           $total.attr('value', recalculateTotal(sc));
      
           //Delete reservation
                //$('#cart-item-'+this.settings.id).remove();
           //optional
           return 'available';
      
         } else if (this.status() == 'unavailable') { //sold
          return 'unavailable';
      
         } else {
          return this.style();
         }
        }
       });

I have changed $('<option selected>...) like this

1. $('<option selected>R'+(this.settings.row+1)+' S'+this.settings.label+' P'+this.settings.data.price+'</option>')

that is, I insert a new figure: "price". Ok. This selction works properly.

I store all the data in a DB MySql using PHP page

1. <?php 
       if (isset($_POST['book'])) {
        $date = $_POST["date"];
        $session = $_POST["session"];
        $counter = $_POST["counter"];
        $total = $_POST["total"];
        $user_id = $_SESSION["id"];
        $film_id = $_GET['id'];
        $seat = (isset($_POST['seat']) ? $_POST['seat']:array());
        if (is_array($seat)) {     
         foreach ($seat as $selectedOption){
          $query = "INSERT INTO booking(USER_ID, FILM_ID, BOOKING_SESSION, BOOKING_DATE, BOOKING_SEAT, BOOKING_PRICE, BOOKING_NUM) 
             VALUES ('$user_id','$film_id','$session','$date','$selectedOption','$total','$counter')";
        
          $result = mysqli_query ($connection,$query)
           or die ("<div class='alert alert-danger' role='alert'>You couldn't execute query</div>"); 
          }
         echo " <div class='alert alert-success' role='success'>
            Congrats your booking has been done! Print the tickets <a href='./fpdf18/generate-pdf.php?film=$film_id' target='_blank'>here</a>!
           </div>";
        }
        
       } 
       ?>

The question is how to store the PRICE variable to the DB (field SEAT_PRICE)?

This is a screenshot of the HTML inspector