Get new order of sorted rows in a table

You have good examples of sorted lists, but when it comes to the sorted table there are a few things I cannot understand.

// Sortable rows
$('.sorted_table').sortable({
containerSelector: 'table',
itemPath: '> tbody',
itemSelector: 'tr',
placeholder: '<tr class="placeholder"/>'
})

I have a table with tr id=1, id=2, id=3 and so on ..

How do I use the onDrop to get the new order, for instance: 2, 1, 3? I need it in an array in order to send it to mysql.