code: static void initializeDatabaseDriver(String databaseType) {
      String driverClass = System.getProperty(JDBC_DRIVER_CLASS_KEY_PREFIX + databaseType);
      if (driverClass != null) {
        Log.debug("Loading " + driverClass + " to initialize database of type " + databaseType);
        try {
          Class.forName(driverClass);
        } catch (ClassNotFoundException e) {
          throw new RuntimeException("Connection to '" + databaseType + "' database is not possible due to missing JDBC driver. " +
                  "User specified driver class: " + driverClass, e);
        }
        return;
      }
      // use built-in defaults
      switch (databaseType) {
        case HIVE_DB_TYPE:
          try {
            Class.forName(HIVE_JDBC_DRIVER_CLASS);
          } catch (ClassNotFoundException e) {
            throw new RuntimeException("Connection to HIVE database is not possible due to missing JDBC driver.", e);
          }
          break;
        case NETEZZA_DB_TYPE:
          try {
            Class.forName(NETEZZA_JDBC_DRIVER_CLASS);
          } catch (ClassNotFoundException e) {
            throw new RuntimeException("Connection to Netezza database is not possible due to missing JDBC driver.", e);
          }
          break;
        default:
          //nothing to do
      }
    }
docs: Initializes database driver for databases with JDBC driver version lower than 4.0
  
  @param databaseType Name of target database from JDBC connection string