/// <summary>
 /// 插入用户;
 /// </summary>
 /// <param name="user">用户</param>
 /// <returns>受影响行数</returns>
 public int Insert(User user)
 => EfHelper.Save(user, EntityState.Added, "您提交的用户号已存在");
 /// <summary>
 /// 更新用户;
 /// </summary>
 /// <param name="user">用户</param>
 /// <returns>受影响行数</returns>
 public int Update(User user)
 => EfHelper.Save(user, EntityState.Modified);