public function copy() 
{ 
  $id=$this->input->get('id'); 
  $this->db->select('column_name1, column_name2,'); 
  $this->db->from('tblname'); 
  $this->db->where('id',$id); 
  $query = $this->db->get(); 
  foreach($query->result() as $row){ 
    $this->db->insert('tblname',$row); 
    redirect('your-url'); } 
}