Question

I want crate 3 multiple select box that when user select value of select box 1 , select box 2 values loaded and when select value of select box 2 , select box 3 values loaded

Answer 1

You can try using ajax to dynamically load the next selectbox-content. Think of something like this(done using jquery):

$("#first-select").change(function(){
    $.ajax(
    {
        url: 'getNextSelectbox.php',
        data: 'selectbox=1&selection=' + $(this).text(),
        dataType: 'POST',
        success: function(html)
        {
            $("#second-select").html(html);
        }
    });
});

You might want to change this so it does how you prefer it 🙂