ASP.NET C#中如何按Status列降序排序DataSet内的DataTable

方法一：通过DataView排序后生成新的DataTable #

你之前的代码错误在于在填充DataSet之前就尝试操作DataView，此时Myds.Tables[0]还无数据，排序自然不生效。正确流程是先填充数据，再对DataTable的DefaultView设置排序规则，最后将排序后的DataView转为新DataTable：

修改后的完整代码：

[WebMethod(EnableSession = true)]
public List<TaskListClass> getTasks() {
  var userId = Session["UserId"].ToString();
  List<TaskListClass> objB = new List<TaskListClass>();
  try {
    using(var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["DBConnString"].ToString())) {
      connection.Open();
      DataSet Myds = new DataSet();
      
      SqlDataAdapter sqldr = new SqlDataAdapter();
      string ProcName = "getTasks";
      SqlCommand cmd = new SqlCommand(ProcName, connection);
      cmd.CommandType = CommandType.StoredProcedure;
      cmd.Parameters.Add("@userId", SqlDbType.VarChar, 900).Value = userId;
      sqldr.SelectCommand = cmd;
      sqldr.Fill(Myds);
      
      // 填充数据后处理排序
      DataTable originalDt = Myds.Tables[0];
      // 设置Status列降序排序
      originalDt.DefaultView.Sort = "Status DESC";
      // 将排序后的视图转为新DataTable
      DataTable sortedDt = originalDt.DefaultView.ToTable();

      for (int i = 0; i < sortedDt.Rows.Count; i++) {
        objB.Add(new TaskListClass() {
          Id = Convert.ToString(sortedDt.Rows[i]["Id"]),
          Subject = Convert.ToString(sortedDt.Rows[i]["Subject"]),
          Customer = Convert.ToString(sortedDt.Rows[i]["Customer"]),
          Sender = Convert.ToString(sortedDt.Rows[i]["Sender"]),
          Receiver = Convert.ToString(sortedDt.Rows[i]["Receiver"]),
          Priority = Convert.ToString(sortedDt.Rows[i]["Priority"]),
          StartDate = Convert.ToString(sortedDt.Rows[i]["StartDate"]),
          EndDate = Convert.ToString(sortedDt.Rows[i]["EndDate"]),
          Status = Convert.ToString(sortedDt.Rows[i]["Status"]),
          OnProgress = Convert.ToString(sortedDt.Rows[i]["OnProgress"]),
        });
      }
    }
  } catch (Exception e) {
    msg = e.ToString();
  }
  return objB;
}

方法二：直接对List排序 #

如果不需要保留DataTable的排序状态，也可以在数据转为List后直接排序，代码更简洁：

[WebMethod(EnableSession = true)]
public List<TaskListClass> getTasks() {
  var userId = Session["UserId"].ToString();
  List<TaskListClass> objB = new List<TaskListClass>();
  try {
    using(var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["DBConnString"].ToString())) {
      connection.Open();
      DataSet Myds = new DataSet();
      
      SqlDataAdapter sqldr = new SqlDataAdapter();
      string ProcName = "getTasks";
      SqlCommand cmd = new SqlCommand(ProcName, connection);
      cmd.CommandType = CommandType.StoredProcedure;
      cmd.Parameters.Add("@userId", SqlDbType.VarChar, 900).Value = userId;
      sqldr.SelectCommand = cmd;
      sqldr.Fill(Myds);
      
      DataTable dt = Myds.Tables[0];

      for (int i = 0; i < dt.Rows.Count; i++) {
        objB.Add(new TaskListClass() {
          Id = Convert.ToString(dt.Rows[i]["Id"]),
          Subject = Convert.ToString(dt.Rows[i]["Subject"]),
          Customer = Convert.ToString(dt.Rows[i]["Customer"]),
          Sender = Convert.ToString(dt.Rows[i]["Sender"]),
          Receiver = Convert.ToString(dt.Rows[i]["Receiver"]),
          Priority = Convert.ToString(dt.Rows[i]["Priority"]),
          StartDate = Convert.ToString(dt.Rows[i]["StartDate"]),
          EndDate = Convert.ToString(dt.Rows[i]["EndDate"]),
          Status = Convert.ToString(dt.Rows[i]["Status"]),
          OnProgress = Convert.ToString(dt.Rows[i]["OnProgress"]),
        });
      }
      
      // 对List按Status降序排序
      objB = objB.OrderByDescending(t => t.Status).ToList();
    }
  } catch (Exception e) {
    msg = e.ToString();
  }
  return objB;
}

额外优化建议 #

1. 如果Status是数值类型（如int），建议将TaskListClass中的Status属性也设置为对应数值类型，避免字符串排序的字典序偏差；
2. 最高效的方式是直接在存储过程getTasks中添加ORDER BY Status DESC，让数据库直接返回排序后的数据，减少内存排序开销。

内容的提问来源于stack exchange，提问作者Emmon