How To I Retrive The State(Dropdownlist) Based On The Country (Dropdownlist) Using Ajax Update Panel

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ASP.NET

Dear Sir/Madam,
I want to select country, based on the country the corresponding states wants to retrieve... But i have got everything whatever stored in the database table...

This is my design page

    <form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
   

    <div>
        
        
            <asp:UpdatePanel ID="CountryPanel" runat="server">
                <contenttemplate>
                    <tr>
                        <td>
                            <asp:Label ID="lbl_Country" runat="server" Text="Country" Width="150px">
                        </td>
                        <td>
                            <asp:DropDownList ID="DDL_Country" runat="server" Width="150px" 
                                AutoPostBack="true" AppendDataBoundItems="true" 
                                onselectedindexchanged="DDL_Country_SelectedIndexChanged">
                            
                        </td>
                    </tr>
                </contenttemplate>
                <triggers>
                    <asp:AsyncPostBackTrigger ControlID="DDL_Country" />
                </triggers>
            
            <br />

        <asp:UpdatePanel ID="StatePanel" runat="server">
        <contenttemplate>
        <tr>
            
        <td>
        <asp:Label ID="lbl_State" runat="server" Text="State" Width="150px">
        </td>
            <asp:DropDownList ID="DDL_State" runat="server" Width="150px" 
              AutoPostBack="true" AppendDataBoundItems="true" onselectedindexchanged="DDL_State_SelectedIndexChanged">
            
        <td>
        </td>
        </tr>
        </contenttemplate>
        <triggers>
        <asp:AsyncPostBackTrigger ControlID="DDL_State" />

        </triggers>
        
        <br />
        
    </div>
    </form>
</body>

This is my code behind file

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        Country();
    }
}

public void Country()
{
    con.Open();
    cmd = new SqlCommand("select CountryId,Country from Country", con);
    dr = cmd.ExecuteReader();
    DDL_Country.DataSource = dr;
    DDL_Country.Items.Clear();
    DDL_Country.Items.Add("-Select Country-");
    DDL_Country.DataTextField = "Country";
    DDL_Country.DataValueField = "CountryId";
    DDL_Country.DataBind();
    con.Close();

}

public void State()
{
    con.Open();
    cmd = new SqlCommand("select state_ID,State_Name from stat", con);
    dr = cmd.ExecuteReader();
    DDL_State.DataSource = dr;
    DDL_State.Items.Clear();
    DDL_State.Items.Add("-Select State-");
    DDL_State.DataTextField = "State_Name";
    DDL_State.DataValueField = "state_ID";
    DDL_State.DataBind();
    con.Close();

}

protected void DDL_Country_SelectedIndexChanged(object sender, EventArgs e)
{
    State();

}

Please help me...


Consider i have countries like India , Pakistan, Srilanka...
If i select India means India's states like Tamilnadu, Karnataka only want to retrieve from the database. But in my case all the states (India,Pakistan,Srilanka) retrieving from the db...

Thanks in Advance...