如何在asp.net中点击按钮后在下拉列表中存储值？

Question

我已经创建了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TeamName时，第二个下拉列表应该自动填充团队成员名称，并且在按钮单击数据应该插入数据库之后，它对第一次按钮点击工作正常，但第二次在同一页面上“TeamName”下拉列表不工作显示部门名称，突然它会丢失。所以请告诉我我需要做什么来解决这个问题？

以下是我做到了实现这一任务

User.aspx page code: 

代码

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(); 

      } 

     } 

Answer 1

成功保存后，我会重新绑定“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，您可以使用该方法，具体取决于ClearFields()的作用。