Populate ASP.Net DropDownList based on RadioButtonList selection using C# and VB.Net

Hey democloud,

Please refer below sample.

HTML

<label>
    Select Type of Client</label>
<asp:RadioButtonList ID="RadioButtonList1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="RadioButtonList1_SelectedIndexChanged">
    <asp:ListItem Value="Customers">A</asp:ListItem>
    <asp:ListItem Value="Employees">B</asp:ListItem>
</asp:RadioButtonList>
<asp:DropDownList runat="server" ID="ddlCountry">
</asp:DropDownList>

Namespaces

C#

using System.Data;
using System.Data.SqlClient;
using System.Configuration;

VB.Net

Imports System.Data.SqlClient
Imports System.Data

Code

C#

protected void RadioButtonList1_SelectedIndexChanged(object sender, EventArgs e)
{
    string query = "SELECT Country From " + RadioButtonList1.SelectedValue + "";
    DataTable dt = GetData(query);
    ddlCountry.DataSource = dt;
    ddlCountry.DataTextField = "Country";
    ddlCountry.DataValueField = "Country";
    ddlCountry.DataBind();
}

private static DataTable GetData(string query)
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand(query, con))
        {
            using (SqlDataAdapter da = new SqlDataAdapter(cmd))
            {
                using (DataTable dt = new DataTable())
                {
                    da.Fill(dt);
                    return dt;
                }
            }
        }
    }
}

VB.Net

Protected Sub RadioButtonList1_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
    Dim query As String = "SELECT Country From " & RadioButtonList1.SelectedValue & ""
    Dim dt As DataTable = GetData(query)
    ddlCountry.DataSource = dt
    ddlCountry.DataTextField = "Country"
    ddlCountry.DataValueField = "Country"
    ddlCountry.DataBind()
End Sub

Private Shared Function GetData(ByVal query As String) As DataTable
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Using cmd As SqlCommand = New SqlCommand(query, con)
            Using da As SqlDataAdapter = New SqlDataAdapter(cmd)
                Using dt As DataTable = New DataTable()
                    da.Fill(dt)
                    Return dt
                End Using
            End Using
        End Using
    End Using
End Function

Screenshot