Working with AJAX, plaese help me out

[eluser]afro[/eluser]
I have fields in my webpage that i want to be
load from the database when one on the fields has been filled by the user using AJAX

The fields are as follows

Code:

StaffId............. StaffName................

Department.......... Leave Balance............

I want when the StaffId is filled by the user, the rest of the fields are auto filled.

The staff table is has as follows.

Code:

+--------|---------|-------|--------|----------|------------+
|StaffId |FirstName|Surname|LastName|Department|LeaveBalance|
+--------|---------|-------|--------|----------|------------+

I have tried out this but does not work totally so can some help me out

Code:

function get_staff_id(staffid) {
    
    var p = {};
     p[staffid] = staffid

    $('#leaveaplication').find('#staffid').load(index.php/home/load_staff_data,p,function(str){

     });
}

$(document).ready(function()
{
$('#leaveaplication').find('#staffid').blur(function()
  {
        alert "Hello world";                              
    var staffid = $('#staffid').val();
  
    $.post('/index.php/home/load_staff_data',
      { 'staffid':staffid },

function(result) {
        $('#staffdetails').replaceWith('');
        
        if (results) {
          $('#staffid').after('<div id="bad_username" style="color:red;">' +
            '<p>(That StaffId does not exits. Please type the correct Staff Id:)</p></div>');
        }
      }
    );
  });  

});

Code:

public function load_staff_data()
    {
    $this->load->model('user_model', '', TRUE);
    $staffid = trim($_POST['staffid']);
    $results = $this->user_model->get_staff_data($staffid);
    }

Code:

public function get_staff_data($staffid)
{
    $this->db->select('StaffId,StaffName, Department, LeaveBalance');
    $this->db->where('StaffId', $staffid);
     $query = $this->db->get('staff');
    $row = $query->row();
    
    $results[record][$row->StaffName][StaffName] = $row->StaffName;
    $results[record][$row->Department][Department] = $row->Department;
    $results[record][$row->LeaveBalance][LeaveBalance] = $row->LeaveBalance;
    
    return $results;
}