code: @Override
  	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
  		ApptentiveLog.d(DATABASE, "Upgrade database from %d to %d", oldVersion, newVersion);
  		try {
  			DatabaseMigrator migrator = createDatabaseMigrator(oldVersion, newVersion);
  			if (migrator != null) {
  				migrator.onUpgrade(db, oldVersion, newVersion);
  			}
  		} catch (Exception e) {
  			ApptentiveLog.e(DATABASE, e, "Exception while trying to migrate database from %d to %d", oldVersion, newVersion);
  			logException(e);
  
  			// if migration failed - create new table
  			db.execSQL(SQL_DELETE_PAYLOAD_TABLE);
  			onCreate(db);
  		}
  	}
docs: This method is called when an app is upgraded. Add alter table statements here for each version in a non-breaking
  switch, so that all the necessary upgrades occur for each older version.