Bind (Populate) ListView inside GridView in ASP.Net

Please refer below code.

HTML

<div>
    <asp:ListView ID="ListView1" runat="server" GroupItemCount="3" GroupPlaceholderID="groupPlaceHolder1"
        ItemPlaceholderID="itemPlaceHolder1" OnItemDataBound="DataBound" DataKeyNames="CustomerId">
        <LayoutTemplate>
            <table>
                <asp:PlaceHolder runat="server" ID="groupPlaceHolder1"></asp:PlaceHolder>
            </table>
        </LayoutTemplate>
        <GroupTemplate>
            <tr>
                <asp:PlaceHolder runat="server" ID="itemPlaceHolder1"></asp:PlaceHolder>
            </tr>
        </GroupTemplate>
        <ItemTemplate>
            <td>
                <table cellpadding="2" cellspacing="0" border="1" style="width: 200px; height: 100px;
                    text-align: center">
                    <tr>
                        <td>
                            <b><u><span class="name">
                                <%# Eval("ContactName") %></span></u></b>
                        </td>
                    </tr>
                    <tr>
                        <td>
                            <asp:GridView ID="gvDetails" runat="server" AutoGenerateColumns="false">
                                <Columns>
                                    <asp:BoundField DataField="City" HeaderText="City" />
                                    <asp:BoundField DataField="PostalCode" HeaderText="PostalCode" />
                                    <asp:BoundField DataField="Country" HeaderText="Country" />
                                </Columns>
                            </asp:GridView>
                        </td>
                    </tr>
                </table>
            </td>
        </ItemTemplate>
    </asp:ListView>
</div>

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        string query = "SELECT top 10 CustomerId,ContactName FROM Customers";
        ListView1.DataSource = this.GetData(query);
        ListView1.DataBind();
    }
}

private DataSet GetData(string query)
{
    string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    SqlCommand cmd = new SqlCommand(query);
    using (SqlConnection con = new SqlConnection(conString))
    {
        using (SqlDataAdapter sda = new SqlDataAdapter())
        {
            cmd.Connection = con;
            sda.SelectCommand = cmd;
            using (DataSet ds = new DataSet())
            {
                sda.Fill(ds);
                return ds;
            }
        }
    }
}

protected void DataBound(object sender, ListViewItemEventArgs e)
{
    int i = 0;
    if (e.Item.ItemType == ListViewItemType.DataItem)
    {
        string customerId = ListView1.DataKeys[i].Value.ToString();
        string query = "SELECT * FROM Customers WHERE CustomerId = '" + customerId + "';";
        GridView gvDetails = (e.Item.FindControl("gvDetails") as GridView);
        gvDetails.DataSource = GetData(query);
        gvDetails.DataBind();
        i++;
    }
}

VB

Protected Sub Page_Load(sender As Object, e As EventArgs)
	If Not IsPostBack Then
		Dim query As String = "SELECT top 10 CustomerId,ContactName FROM Customers"
		ListView1.DataSource = Me.GetData(query)
		ListView1.DataBind()
	End If
End Sub

Private Function GetData(query As String) As DataSet
	Dim conString As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
	Dim cmd As New SqlCommand(query)
	Using con As New SqlConnection(conString)
		Using sda As New SqlDataAdapter()
			cmd.Connection = con
			sda.SelectCommand = cmd
			Using ds As New DataSet()
				sda.Fill(ds)
				Return ds
			End Using
		End Using
	End Using
End Function

Protected Sub DataBound(sender As Object, e As ListViewItemEventArgs)
	Dim i As Integer = 0
	If e.Item.ItemType = ListViewItemType.DataItem Then
		Dim customerId As String = ListView1.DataKeys(i).Value.ToString()
		Dim query As String = (Convert.ToString("SELECT * FROM Customers WHERE CustomerId = '") & customerId) + "';"
		Dim gvDetails As GridView = TryCast(e.Item.FindControl("gvDetails"), GridView)
		gvDetails.DataSource = GetData(query)
		gvDetails.DataBind()
		i += 1
	End If
End Sub

Screenshot