function item_add(tag){
  var id = tag.id;
  var table = tag.name;
  window.location.href = "./modify/item_add.php?booking_id=" + id + "&table=" + table;
}

function item_subtract(tag){
    var id = tag.id;
    var table = tag.name;
    window.location.href = "./modify/item_subtract.php?booking_id=" + id + "&table=" + table;
}

function item_del(tag){
    var id = tag.id;
    var table = tag.name;
    window.location.href = "./modify/item_del.php?booking_id=" + id + "&table=" + table;
}

function item_modify(tag){
    var id = tag.id;
    var quantity = tag.value;
    var table = tag.name;
    window.location.href = "./modify/item_modify.php?booking_id=" + id + "&quantity=" + quantity + "&table=" + table;
}