如何在asp.net中单击按钮后将值存储在下拉列表中？答案

【问题标题】：How to store values in drop down list after button click in asp.net?如何在asp.net中单击按钮后将值存储在下拉列表中？
【发布时间】：2017-10-08 15:59:52
【问题描述】：

我创建了 2 个 DropDownLists 第一个下拉列表包含“TeamName”，第二个包含“TeamMember”名称。要求是当我们从下拉列表中选择特定的团队名称时，第二个下拉列表应自动填充团队成员名称，并且在按钮单击数据后应将数据插入数据库中，第一次按钮单击工作正常，但第二次在同一页面上“团队名称”下拉列表不显示部门名称，突然丢失。所以请告诉我我需要做什么来解决这个问题？？

以下是我为完成此任务所做的代码

User.aspx page code:

User.aspx.cs 页面代码：

 protected void Page_Load(object sender, EventArgs e)
 {
    if (!IsPostBack)
    {
        BindTeamName();
        txtCurrentDate.Text = DateTime.Now.ToString("MM-dd-yyyy");
        txtCurrentDate.ForeColor = System.Drawing.Color.Green;
    }
}
private void BindTeamName()
{
    SqlConnection con = new SqlConnection(SqlString);
    con.Open();
    SqlCommand cmd = new SqlCommand("select * from TeamName", con);
    SqlDataAdapter da = new SqlDataAdapter(cmd);
    DataSet ds = new DataSet();
    da.Fill(ds);
    con.Close();
    ddl1.DataSource = ds;
    ddl1.DataTextField = "TeamName";
    ddl1.DataValueField = "TeamId";
    ddl1.DataBind();
    ddl1.Items.Insert(0, new ListItem("--Select--", "0"));
}
protected void ddl1_SelectedIndexChanged(object sender, EventArgs e)
{
    int TeamId = Convert.ToInt32(ddl1.SelectedValue);
    SqlConnection con = new SqlConnection(SqlString);
    con.Open();
    SqlCommand cmd = new SqlCommand("select * from TeamResource where TeamId=" + TeamId, con);
    SqlDataAdapter da = new SqlDataAdapter(cmd);
    DataSet ds = new DataSet();
    da.Fill(ds);
    con.Close();
    ddl2.DataSource = ds;
    ddl2.DataTextField = "EmpName";
    ddl2.DataValueField = "EmpId";
    ddl2.DataBind();
    ddl2.Items.Insert(0, new ListItem("--Select--", "0"));     
}
protected void btnSubmit_Click(object sender, EventArgs e)
{
    if (Page.IsValid)
    {
        using (SqlConnection con = new SqlConnection(SqlString))
        {

            SqlCommand cmd = new SqlCommand("InsertUserData", con);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@WorkDate", txtCurrentDate.Text);
            cmd.Parameters.AddWithValue("@TeamName", ddl1.SelectedItem.Text);
            cmd.Parameters.AddWithValue("@TeamMember", ddl2.SelectedItem.Text);
            cmd.Parameters.AddWithValue("@AvailableBandwidth", ddlAvailable.SelectedItem.Value);
            con.Open();
            int ReturnCode = (int)cmd.ExecuteScalar();
            if (ReturnCode == -1)
            {
                lblMsg.Text = "Already Data present";
                lblMsg.ForeColor = System.Drawing.Color.Red;
                ClearFields();
            }
            else
            {
                lblMsg.Text = "Data inserted successfully";
                lblMsg.ForeColor = System.Drawing.Color.Green;
                ClearFields();

            }

        }

【问题讨论】：

标签： c# asp.net

【解决方案1】：

我会在成功保存后重新绑定“TeamName”下拉列表。

//btnSubmit_Click
if (ReturnCode == -1)
{
      lblMsg.Text = "Already Data present";
      lblMsg.ForeColor = System.Drawing.Color.Red;
      ClearFields();
}
else
{
      lblMsg.Text = "Data inserted successfully";
      lblMsg.ForeColor = System.Drawing.Color.Green;
      ClearFields();
      BindTeamName(); //re-bind the initial dropdown so you can select a new team
 }

实际上你可以使用任何一种方法，这取决于ClearFields() 的作用。

【讨论】：