比如我想再添加一个单位ID作为分表参数应该如何实现

  /**
     * 获取特定月份的Dao实例
     *
     * @param key
     * @return
     */
    public Dao logDao(String key) {
        Dao dao = ymDaos.get(key);
        if (dao == null) {
            synchronized (this) {
                dao = ymDaos.get(key);
                if (dao == null) {
                    dao = Daos.ext(this.dao(), key);
                    dao.create(Sys_log.class, false);
                    ymDaos.put(key, dao);
                    try {
                        Daos.migration(dao, Sys_log.class, true, false);
                    } catch (Throwable e) {
                    }
                }
            }
        }
        return dao;
    }