Moving div Up and Down Changing ID Num using Javascript/Jquery

I want to be able to change ID when moving the div up and down so then I can submit them numbers to MySQLi...

So basically from

<div id="1" class='col1'>1</div>
<div id="2" class='col2'>2</div>
<div id="3" class='col3'>3</div>
<div id="4" class='col4'>4</div>
<div id="5" class='col5'>5</div>

to

<div id="5" class='col1'>1</div>
<div id="2" class='col2'>2</div>
<div id="4" class='col3'>3</div>
<div id="1" class='col4'>4</div>
<div id="3" class='col5'>5</div>

or something like that...

HTML

<div id='items'>
                <div id="1" class='col1'>1</div>
                <div id="2" class='col2'>2</div>
                <div id="3" class='col3'>3</div>
                <div id="4" class='col4'>4</div>
                <div id="5" class='col5'>5</div>

            </div>

    <a href="#" id="up">Up</a>
    <a href="#" id="down">Down</a>

JS

    $(document).ready(function(){
        var selected=0;

         var itemlist = $('#items');
        var len=$(itemlist).children().length; 

        $("#items div").click(function(){
            selected= $(this).index();
            alert("Selected item is " + $(this).text());
        });


         $("#up").click(function(e){
           e.preventDefault();
           if(selected>0)
            {
                jQuery($(itemlist).children().eq(selected-1)).before(jQuery($(itemlist).children().eq(selected)));
                selected=selected-1;
            }
        });

         $("#down").click(function(e){
             e.preventDefault();
            if(selected < len)
            {
                jQuery($(itemlist).children().eq(selected+1)).after(jQuery($(itemlist).children().eq(selected)));
                selected=selected+1;
            }
        });




    });

CSS

    #items div{
      width:100px;
      height:20px;
      border:1px solid #000;
      margin-top:2px;
      text-align:center
    }
    div .col1{
      background-color:#000;
      color:#fff
    }
    .col2{
      background-color:#0f0;
    }
    .col3{
      background-color:#00f;
      color:#fff
    }
    .col4{
      background-color:#f00;
      color:#fff
    }
    .col5{
      background-color:#ff0;

    }

Everything moves but somehow I need it to change the ID if possible so then it will sort in that order.

Is this possible? If so can someone help me please.