Do we have to change the code at the build time for each different platform in phonegap?

I want to know if I have to change the code while building the application for different platforms in phonegap. Suppose I have created the app which include database,also calling the web service(API),then do all that code changes as we change the platform? Can we have a code that is build one time and that works for all platforms such as android, ios and windows and if it is possible than how? I want to get clear about phonegap that do we have differnet ways for calling a web service or storing data in database for differnt platforms? I am using IntelXDK for building phonegap app.