HTREEITEM root = m_Tree.GetRootItem();
m_Tree.DeleteAllItems();
DB.SQL_Ausfuehren("SELECT * FROM Kategorien WHERE Parentkat=0");
while(!DB.EOA())
{
    HTREEITEM newItem = m_Tree.InsertItem(DB.GetItem(1));
    m_Tree.SetItemData(newItem, data);
    DB.NextRow();
}