code: public static void configureDB(JobConf job, String driverClass, String dbUrl
        , String userName, String passwd) {
  
      job.set(DRIVER_CLASS_PROPERTY, driverClass);
      job.set(URL_PROPERTY, dbUrl);
      if(userName != null)
        job.set(USERNAME_PROPERTY, userName);
      if(passwd != null)
        job.set(PASSWORD_PROPERTY, passwd);    
    }
docs: Sets the DB access related fields in the JobConf.
  @param job the job
  @param driverClass JDBC Driver class name
  @param dbUrl JDBC DB access URL.
  @param userName DB access username
  @param passwd DB access passwd