如何在C＃中的dropdown selectindexchange上刷新表

问题描述

实际上，我有一个下拉列表，在selectindexchange的表的drowndown值得到更改，但下次当我再次选择下拉列表的下拉值时，表格中仍然保留下来值，我使用autopostback刷新下拉列表



我尝试了什么：

Actually , i have one dropdown , on selectindexchange of drowndown value of table get change , but next time when i again selectindexchange of dropdown previous value remain in table , i am using autopostback to refresh dropdown

What I have tried:

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
        string query = "select attenday , slot , present from attendance where name = '" + DropDownList1.Text + "'";

        DataTable dtAdmin = new DataTable();
        SqlDataAdapter da;
        da = new SqlDataAdapter(query, con);
        da.Fill(dtAdmin);
        if (dtAdmin.Rows.Count > 0)
           {
                SqlCommand cmd = new SqlCommand(query, con);
                 SqlDataReader dbr;
              
                    con.Open();
                    dbr = cmd.ExecuteReader();
                    while (dbr.Read())
                    {
                        string attenday = (string)dbr["attenday"].ToString();
                        string slot = (string)dbr["slot"].ToString();
                        string presentday = (string)dbr["present"].ToString();

                       
                        if (attenday == "1")
                        {
                            DropDownList2.Text = slot;
                            Label1.Text = presentday;
                        }

                        else if (attenday == "2")
                        {
                            DropDownList3.Text = slot;
                            Label3.Text = presentday;
                        }

                        else if (attenday == "3")
                        {
                            DropDownList4.Text = slot;
                            Label5.Text = presentday;
                        }

                        else if (attenday == "4")
                        {
                            DropDownList5.Text = slot;
                            Label7.Text = presentday;
                        }

                        else if (attenday == "5")
                        {
                            DropDownList6.Text = slot;
                            Label9.Text = presentday;
                        }

                        else if (attenday == "6")
                        {
                            DropDownList7.Text = slot;
                            Label2.Text = presentday;
                        }


                        else if (attenday == "7")
                        {
                            DropDownList8.Text = slot;
                            Label4.Text = presentday;
                        }


                        else if (attenday == "8")
                        {
                            DropDownList9.Text = slot;
                            Label6.Text = presentday;
                        }


                        else if (attenday == "9")
                        {
                            DropDownList10.Text = slot;
                            Label8.Text = presentday;
                        }

                        else if (attenday == "10")
                        {
                            DropDownList11.Text = slot;
                            Label10.Text = presentday;
                        }
                      

                      
                    }

                    dbr.Close();

推荐答案

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
       // Call Your Function
    }
}

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