Connect multiple database and call in code igniter

Paypal Integration in Codeigniter



<form name="paypalFrm" id="paypalFrm_<?php echo $subscribe[$i]->subscriptionpackageID;?>" action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">
                                            <input type="hidden" name="cmd" value="_ext-enter">
                                            <input type="hidden" name="redirect_cmd" value="_xclick"> //useful to get your custom variable back in response
                                           
                                            <input type="hidden" name="return" value="<?php echo base_url('clinic/paid');?>">
                        //set url name where you can check for your response
                                            <input type="hidden" name="cancel_return" value="<?php echo base_url('clinic/cancel');?>">
                        // set url to check response when user denied or cancel payment and want to back

                                            <input type="hidden" name="notify_url" value="<?php echo base_url('clinic/notify');?>">
                        // to check please set send email logic and check for     response                                            
                                            <input type="hidden" name="business" value="adc.haren@gmail.com">
                        //your bussiness acoount in which payment is done
                        //account in which you want to get paid (owers account)
   
                                            <input type="hidden" name="item_name" value="Purchage 10 docs">
                                            <input type="hidden" name="quantity_1" value="1">
                                           
                                            <input type="hidden" name="currency_code" value="USD">
                                            <input type="hidden" name="amount" value="1">   //your amount
                                         <input type="hidden" name="custom" value="<?php echo $userinfo[0]->userId;?>">
                                           
                                           
                                           
                                            <input type="hidden" name="on1" value="<?php echo $userinfo[0]->firstName;?>">
                                            <input type="hidden" name="on0" value="<?php echo $userinfo[0]->userId;?>">
                                            <input type="hidden" name="on2" value="<?php echo $subscribe[$i]->Amount;?>">
                                            <input type="hidden" name="on3" value="<?php echo $subscribe[$i]->packageName;?>">
                                           
                                    </form>

********** PHP code ***********

 public function paid()
         {
             $uid=$this->session->userdata('userId');
            
             if(isset($_REQUEST['payment_status']))
             {
                 
                 echo "<pre>"; print?_r($_REQUEST['payment_status']);
               Your bussiness logic
             }
             else
             {
               Your bussiness logic
             }
         }
 public function cancel()
         {
            your bussiness logic if client do ot want to pay
         }
        
          public function notify()
          {
             
            echo "<pre>";             print_r($_REQUEST);die;  
          }