/// <summary> /// 获取第一个或者null的实体 /// </summary> /// <typeparam name="S">泛型类型</typeparam> /// <param name="where">条件</param> /// <param name="order">排序</param> /// <param name="isAsc">是否升序</param> /// <returns></returns> public T FirstOrDefault(Expression <Func <T, bool> > where = null) { return(_baseDal.FirstOrDefault(where)); }