Binding RadPanelBar to an SQL data source is very easy - just create your connection string, query the database and get the result-set into a DataTable, DataSet or DataView. Assign the result to the DataSource property of the panelbar and call the DataBind() method.

The properties you need to set to define the ID -> ParentID hierarchy are DataFieldID and DataFieldParentID respectively: just set them to the SQL data source columns defining the ID / ParentID relation. You will need to set the DataTextField property of the panelbar to the name of the column holding the name of the respective item.

To map additional columns from the SQL data table to properties of the respective item, you need to hook the ItemDataBound event. The event arguments passed to the event - e.Item and e.Item.DataItem - hold the instance of the item being bound and the DataItem associated with the item. You can then map a property from the DataItem (make sure to cast the DataItem object to your respetive data type first - usually DataRowView) to the property of the RadPanelItem class.