To Generate serial number

Hi, To create code for auto generate number base on quantity, For example, I put quantity '999' into form and after I click "submit" system auto generate serial number 1~999 to database table (product_serial_number). database table : product_serial_number serial_id | serial_group_id | product_number | serial_number 1 | 55 | 54321 | 1 2 | 55 | 54321 | 2 3 | 55 | 54321 | 3 4 | 55 | 54321 | 4 5 | 55 | 54321 | 5 6 | 55 | 51112 | 1 7 | 55 | 51112 | 2 8 | 55 | 51112 | 3 9 | 55 | 51112 | 4 10 | 55 | 51112 | 5 11 | 55 | 51112 | 6 12 | 55 | 51112 | 7 13 | 55 | 51112 | 8 14 | 55 | 51112 | 9 15 | 55 | 51112 | 10 16 | 55 | 51112 | 11 Form [login to view URL] : <?php echo form_open(base_url() . '[login to view URL]', array( 'class' => 'form-horizontal', 'method' => 'post', 'id' => 'generate_serial', 'enctype' => 'multipart/form-data' )); ?> <div class="panel-body"> <input type="hidden" name="product" value="<?php echo $product; ?>"> <input type="hidden" name="category" value="<?php echo $this->crud_model->get_type_name_by_id('product',$product,'category'); ?>"> <input type="hidden" name="sub_category" value="<?php echo $this->crud_model->get_type_name_by_id('product',$product,'sub_category'); ?>"> <div class="form-group"> <label class="col-sm-4 control-label" for="demo-hor-1"><?php echo translate('current_quantity');?></label> <div class="col-sm-6"> <input type="number" disabled value="<?php echo $this->crud_model->get_type_name_by_id('product',$product,'current_stock'); ?>" class="form-control totals"> </div> </div> </div> </form> In Controller [login to view URL] : } else if ($para1 == 'do_generate') { $data['serial_group_id'] = $this->input->post('serial_group_id'); $data['product_number'] = $this->input->post('product_number'); $data['serial_number'] = $this->input->post('serial_number'); $this->db->insert('product_serial_number', $data); recache(); } } elseif ($para1 == 'generate') { $this->load->view('back/admin/stock_serial_generate');