Change Index value in dropdownlist the repeater content cahnge

Question

I want to display data in repeater based on the dropdownlist selected index. For example, when i choose "Help" item in dropdownlist the repeater will display the help categories content in database. Else choose Car will display car categories. May I know how can I control my dropdownlist?

if (!IsPostBack)
        {
            try
            {
                MySqlConnection connStr = new MySqlConnection();
                connStr.ConnectionString = "Server = localhost; Database = healthlivin; Uid = root; Pwd = khei92;";
                String stSearch = "SELECT t.title, p.userName, t.threadID FROM thread t , person p WHERE p.PersonID = t.PersonID AND t.categories = @categories";
                MySqlCommand cmdSearch = new MySqlCommand(stSearch, connStr);
                cmdSearch.Parameters.AddWithValue("@categories", categoriesDropDownList.SelectedValue);

                connStr.Open();

                MySqlDataReader dtrRead = cmdSearch.ExecuteReader();
                categoriesRepeater.DataSource = dtrRead;
                categoriesRepeater.DataBind();
                dtrRead.Close();
                dtrRead = null;
                //MessageBox.Show("Connected");
                connStr.Close();
            }
            catch (Exception ex)
            {
                //MessageBox.Show("X Connected" + ex.ToString());
            }


        } 

Answer 1

You have to make AutoPostBack="true" of dropdown and bind SelectedIndexChanged event where you will get the selectedIndex and use that to bind the repeater.

Html

<asp:DropDownList ID="ddl" runat="server" AutoPostBack="True" 
    onselectedindexchanged="itemSelected">
</asp:DropDownList>

Code behind

protected void itemSelected(object sender, EventArgs e)
{
    if(ddl.SelectedIndex == 1)
    {
        //Bind Help   
    }        
    else
    if(ddl.SelectedIndex == 2)
    {
        //Bind Car
    }        
}