ASP.NET日历保持刷新页面

Question

我已经实现了一个asp.net日历，以便能够选择日期并将其保存在数据库中。但是，每次按下它都会刷新整个页面。 例如，如果我按下日期刷新，如果我按箭头移动到下个月，该页面也会刷新。

如何阻止用户在每次更改时刷新它？

以下是代码：

HTML：

<tr>
  <td>Start Date :</td>
</tr>
<tr>
  <td><asp:Calendar ID="StartDate" runat="server"></asp:Calendar></td>
</tr>

<tr>
  <td>End Date :</td>
</tr>
<tr>
  <td><asp:Calendar ID="EndDate" runat="server"></asp:Calendar></td>
</tr>

C＃：

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class admin_EventsUpdate : System.Web.UI.Page
{
     int EventId = 0;

    protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["AdminSession"] == null)
            Response.Redirect("~/admin/index.aspx");

        EventId = Convert.ToInt32(Request["EventId"].ToString());

        if (!IsPostBack && EventId != 0)
        {
            Submit.Text = "Update";

            DataSet ds = Admin.GetEvent(EventId);

            foreach (DataRow row in ds.Tables[0].Rows)
            {
                if (row["startdate"].ToString() !="" )
                {
                    StartDate.SelectedDate = Convert.ToDateTime(row["startdate"].ToString());
                    StartDate.VisibleDate = StartDate.SelectedDate;
                }

                if (row["enddate"].ToString() != "")
                {
                    EndDate.SelectedDate = Convert.ToDateTime(row["enddate"].ToString());
                    EndDate.VisibleDate = EndDate.SelectedDate;
                }

            }
        }


    }


    protected void Update_Click(object sender, EventArgs e)
    {
            string SD;
            string ED;

            if (StartDate.SelectedDate.Date == DateTime.MinValue.Date)
                SD = "";
            else
            {
                DateTime sdt = StartDate.SelectedDate;
                SD = sdt.Date.Year + "-" + sdt.Date.Month + "-" + sdt.Date.Day;
            }
            if (EndDate.SelectedDate.Date == DateTime.MinValue.Date)
                ED = "";
            else
            {
                DateTime sdt = EndDate.SelectedDate;
                ED = sdt.Date.Year + "-" + sdt.Date.Month + "-" + sdt.Date.Day;
            }
        if (EventId != 0)
              Admin.UpdateEvent(SD, ED);

        else
             Admin.AddEvent(SD, ED);

        Response.Redirect("~/admin/Events.aspx");
    }
}