Want to know how query is generated in opencart

Hello,
I am newbie in opencart. I want to know is there any way to print post array in controller/model, so I can check all my values are posted properly(for testing purpose). Second thing I want to know how query is generated, so can I print query in opencart, if yes, then how? Actually I am using a modified version of opencart, there were no IP address and session tabs in system->user->api. Some how I was able to create interface for it (copy paste files from original version, name convention is checked everything is proper) but records are not inserted in oc_api_ip.

Since your request is about a general inquiry, the admin/model and catalog/model sub-folders contains countless examples on how to achieve SQL queries with Opencart. As for the APIs, ensure to properly configure them by following these steps:

viewtopic.php?f=176&p=733002#p717782
viewtopic.php?f=202&t=199203&p=701487#p701528