In this article I will explain how to implement the ASP.Net AJAX Control Toolkit CascadingDropDown DropDownList control without using Web Service in ASP.Net.
The AJAX CascadingDropDown DropDownList control is not designed to work without Web Services, thus if you cannot use a Web Service in your project and want to implement AJAX Cascading DropDownLists then you will need to make use of ASP.Net AJAX UpdatePanel and ASP.Net DropDownList control with AutoPostBack, so that we can prevent page refresh or PostBack.
Note: If you want to use the ASP.Net AJAX Control Toolkit CascadingDropDown DropDownList control using Web Service in ASP.Net, please refer my article AJAX Cascading DropDownList sample with database using ASP.Net
 
 
Database
Three tables Countries, State and City are created with the following schema.
Countries Table
Implement AJAX CascadingDropdown without Web Service in ASP.Net
 
States Table
Implement AJAX CascadingDropdown without Web Service in ASP.Net
 
Cities Table
Implement AJAX CascadingDropdown without Web Service in ASP.Net
 
Note: You can download the database table SQL by clicking the download link below.
          Download SQL file
 
 
Creating the Database
You will have to simply execute the script named CreateCascadingDatabase.sql stored in the SQL Folder of the attached sample and it will create the complete database with data.
 
 
HTML Markup
Below is the HTML Markup which contains three ASP.Net DropDownList controls each for Country, State and City. I have placed all the three DropDownLists inside ASP.Net UpdatePanel control to avoid full PostBack and make use of AJAX.
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <table>
            <tr>
                <td>Country:</td>
                <td><asp:DropDownList ID="ddlCountries" runat="server" AutoPostBack = "true" OnSelectedIndexChanged = "Country_Changed">
                    </asp:DropDownList>
                </td>
            </tr>
            <tr>
                <td>State:</td>
                <td>
                    <asp:DropDownList ID="ddlStates" runat="server" AutoPostBack = "true" OnSelectedIndexChanged = "State_Changed">
                    </asp:DropDownList>
                </td>
            </tr>
            <tr>
                <td>City:</td>
                <td>
                    <asp:DropDownList ID="ddlCities" runat="server">
                    </asp:DropDownList>
                </td>
            </tr>
        </table>
    </ContentTemplate>
</asp:UpdatePanel>
 
 
Generic function to Bind and populate the ASP.Net DropDownList
Below is the generic function that will be used to populate and bind the ASP.Net DropDownList with data from the SQL Server Database
C#
private void BindDropDownList(DropDownList ddl, string query, string text, string value, string defaultText)
{
    string conString = ConfigurationManager.ConnectionStrings["ConString"].ConnectionString;
    SqlCommand cmd = new SqlCommand(query);
    using (SqlConnection con = new SqlConnection(conString))
    {
        using (SqlDataAdapter sda = new SqlDataAdapter())
        {
            cmd.Connection = con;
            con.Open();
            ddl.DataSource = cmd.ExecuteReader();
            ddl.DataTextField = text;
            ddl.DataValueField = value;
            ddl.DataBind();
            con.Close();
        }
    }
    ddl.Items.Insert(0, new ListItem(defaultText, "0"));
}
 
VB.Net
Private Sub BindDropDownList(ddl As DropDownList, query As String, text As String, value As String, defaultText As String)
    Dim conString As String = ConfigurationManager.ConnectionStrings("ConString").ConnectionString
    Dim cmd As New SqlCommand(query)
    Using con As New SqlConnection(conString)
        Using sda As New SqlDataAdapter()
            cmd.Connection = con
            con.Open()
            ddl.DataSource = cmd.ExecuteReader()
            ddl.DataTextField = text
            ddl.DataValueField = value
            ddl.DataBind()
            con.Close()
        End Using
    End Using
    ddl.Items.Insert(0, New ListItem(defaultText, "0"))
End Sub
 
 
Populating the Country DropDownList
The Country DropDownList is populated on Page_Load event of the page as shown below
C#
protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        string query = "select CountryId, CountryName from Countries";
        BindDropDownList(ddlCountries, query, "CountryName", "CountryId", "Select Country");
        ddlStates.Enabled = false;
        ddlCities.Enabled = false;
        ddlStates.Items.Insert(0, new ListItem("Select State", "0"));
        ddlCities.Items.Insert(0, new ListItem("Select City", "0"));
    }
}
 
VB.Net
Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Dim query As String = "select CountryId, CountryName from Countries"
        BindDropDownList(ddlCountries, query, "CountryName", "CountryId", "Select Country")
        ddlStates.Enabled = False
        ddlCities.Enabled = False
        ddlStates.Items.Insert(0, New ListItem("Select State", "0"))
        ddlCities.Items.Insert(0, New ListItem("Select City", "0"))
    End If
End Sub
 
 
Populating the State DropDownList
The State DropDownList is populated on OnSelectedIndexChanged event of the Country DropDownList as shown below
C#
protected void Country_Changed(object sender, EventArgs e)
{
    ddlStates.Enabled = false;
    ddlCities.Enabled = false;
    ddlStates.Items.Clear();
    ddlCities.Items.Clear();
    ddlStates.Items.Insert(0, new ListItem("Select State", "0"));
    ddlCities.Items.Insert(0, new ListItem("Select City", "0"));
    int countryId = int.Parse(ddlCountries.SelectedItem.Value);
    if (countryId > 0)
    {
        string query = string.Format("select StateId, StateName from States where CountryId = {0}", countryId);
        BindDropDownList(ddlStates, query, "StateName", "StateId", "Select State");
        ddlStates.Enabled = true;
    }
}
 
VB.Net
Protected Sub Country_Changed(sender As Object, e As EventArgs)
    ddlStates.Enabled = False
    ddlCities.Enabled = False
    ddlStates.Items.Clear()
    ddlCities.Items.Clear()
    ddlStates.Items.Insert(0, New ListItem("Select State", "0"))
    ddlCities.Items.Insert(0, New ListItem("Select City", "0"))
    Dim countryId As Integer = Integer.Parse(ddlCountries.SelectedItem.Value)
    If countryId > 0 Then
        Dim query As String = String.Format("select StateId, StateName from States where CountryId = {0}", countryId)
        BindDropDownList(ddlStates, query, "StateName", "StateId", "Select State")
        ddlStates.Enabled = True
    End If
End Sub
 
 
Populating the City DropDownList
The City DropDownList is populated on OnSelectedIndexChanged event of the State DropDownList as shown below
C#
protected void State_Changed(object sender, EventArgs e)
{
    ddlCities.Enabled = false;
    ddlCities.Items.Clear();
    ddlCities.Items.Insert(0, new ListItem("Select City", "0"));
    int stateId = int.Parse(ddlStates.SelectedItem.Value);
    if (stateId > 0)
    {
        string query = string.Format("select CityId, CityName from Cities where StateId = {0}", stateId);
        BindDropDownList(ddlCities, query, "CityName", "CityId", "Select City");
        ddlCities.Enabled = true;
    }
}
 
VB.Net
Protected Sub State_Changed(sender As Object, e As EventArgs)
    ddlCities.Enabled = False
    ddlCities.Items.Clear()
    ddlCities.Items.Insert(0, New ListItem("Select City", "0"))
    Dim stateId As Integer = Integer.Parse(ddlStates.SelectedItem.Value)
    If stateId > 0 Then
        Dim query As String = String.Format("select CityId, CityName from Cities where StateId = {0}", stateId)
        BindDropDownList(ddlCities, query, "CityName", "CityId", "Select City")
        ddlCities.Enabled = True
    End If
End Sub
 
 
Demo
View Demo
 
 
Downloads
You can download the complete source code in VB.Net and C# along with the script to create the database, tables and their contents using the download link provided below
Download Code