该问题的解决方法是使用数据绑定的方法。具体步骤如下：

1. 将外部Listview和内部Listview绑定到数据源

2. 在外部Listview的ItemDataBound事件中，找到内部Listview并绑定数据源

以下是示例代码：

VB.NET：

Protected Sub ListView1_OnItemDataBound(sender As Object, e As ListViewItemEventArgs) Dim innerListView As ListView = CType(e.Item.FindControl("InnerListView"),ListView)

If (innerListView IsNot Nothing) Then
    Dim dataItem As DataRowView = CType(e.Item.DataItem, DataRowView)
    Dim innerData As DataTable = GetInnerData(dataItem("ID"))
            
    innerListView.DataSource = innerData
    innerListView.DataBind()
End If

End Sub

C#：

protected void ListView1_OnItemDataBound(object sender, ListViewItemEventArgs e) { ListView innerListView = e.Item.FindControl("InnerListView") as ListView;

if(innerListView!=null)
{
    DataRowView dataItem = e.Item.DataItem as DataRowView;
    DataTable innerData = GetInnerData(dataItem["ID"]);
            
    innerListView.DataSource = innerData;
    innerListView.DataBind();
}

}