useful links

• example for multiple tables

http://www.androidhive.info/2013/09/android-sqlite-database-with-multiple-tables/

• example for upgrade

http://stackoverflow.com/questions/8133597/android-upgrading-db-version-and-adding-new-table

• dev or prod mode

    if (BuildConfig.DEBUG) {
        System.out.println("dev mode");
    } else {
        System.out.println("prod mode");
    }