public void RefreshSelectedSQLItemSchema(TreeView treeView) { SQLTreeItem item = ((SQLTreeItem)treeView.SelectedItem); item.Items.Clear(); List <string> columnSchemas = _SQLHandler.GetSQlSchemaFromSQLItem(item, ConnectionStr); foreach (string colname in columnSchemas) { item.Items.Add(new SQLTreeItem() { Header = colname, ItemType = SQLTreeItem.SQLType.Schema }); } }