How can I retrieve a reverse order of a tree structure in SQL?

Data and Databases
1

I am dealing with a tree structure in SQL Server 2008, which utilizes ItemID, ParentID, and additional fields.

Presently, my selection procedure displays the hierarchy as follows:

1.
1.1
1.1.1

But I want to adjust it to display the records in reverse order, prioritizing the deepest levels first:

1.1.1.
1.1.
1.
2.2.2.2.2.
2.2.2.2.
2.2.2.
2.2.
2.

Here’s the existing stored procedure I use that fetches the normal hierarchy:

ALTER PROCEDURE [dbo].[Object_SelectDownByRoot]
@ObjectID int
AS
WITH tree (ObjectID, ParentID, ObjectName, ObjectCode, DistrictID, DistrictName,
                CityName, RegionName, StreetName, StreetID, AddressID, ObjectTypeName,
                RouteName, ObjectTypeID, RouteID, AvrgTempIn, Area, Volume,
                ElectricPower, ObjectStatusName, ObjectStatusID, [ControlRoom?], DateBuild,
                [Floor], EncloseName, EncloseID, MaintenanceEval, AdministratorID,
                Administrator, ElectricityPerson, ElectricityPersonID,
                HeatingPersonID, HeatingPerson, HouseNo, FlatNo, ZIP,
                AddressStreet, RouteCode, RouteDescription,
                AddressDescription, StreetID2, CityID, AddressCityName) AS
(
    SELECT
    ObjectID, ParentID, ObjectName, ObjectCode, DistrictID, DistrictName,
                  CityName, RegionName, StreetName, StreetID, AddressID, ObjectTypeName,
                  RouteName, ObjectTypeID, RouteID, AvrgTempIn, Area, Volume,
                  ElectricPower, ObjectStatusName, ObjectStatusID, [ControlRoom?], DateBuild,
                  [Floor], EncloseName, EncloseID, MaintenanceEval, AdministratorID,
                  Administrator, ElectricityPerson, ElectricityPersonID,
                  HeatingPersonID, HeatingPerson, HouseNo, FlatNo, ZIP,
                  AddressStreet, RouteCode, RouteDescription,
                  AddressDescription, StreetID2, CityID, AddressCityName
     FROM dbo.[ObjectQ] ofs
     WHERE( ObjectID = @ObjectID )

     UNION ALL

     SELECT ofs.ObjectID, ofs.ParentID, ofs.ObjectName, ofs.ObjectCode, ofs.DistrictID, ofs.DistrictName,
                  ofs.CityName, ofs.RegionName, ofs.StreetName, ofs.StreetID, ofs.AddressID, ofs.ObjectTypeName,
                  ofs.RouteName, ofs.ObjectTypeID, ofs.RouteID, ofs.AvrgTempIn, ofs.Area, ofs.Volume,
                  ofs.ElectricPower, ofs.ObjectStatusName, ofs.ObjectStatusID, ofs.[ControlRoom?], ofs.DateBuild,
                  ofs.[Floor], ofs.EncloseName, ofs.EncloseID, ofs.MaintenanceEval, ofs.AdministratorID,
                  ofs.Administrator, ofs.ElectricityPerson, ofs.ElectricityPersonID,
                  ofs.HeatingPersonID, ofs.HeatingPerson, ofs.HouseNo, ofs.FlatNo, ofs.ZIP,
                  ofs.AddressStreet, ofs.RouteCode, ofs.RouteDescription,
                  ofs.AddressDescription, ofs.StreetID2, ofs.CityID, ofs.AddressCityName
      FROM dbo.[ObjectQ] ofs
      JOIN tree ON tree.ObjectID = ofs.ParentID
)

SELECT * FROM tree

What modifications are required to achieve the inverted order?

2

there’s another approach - add a depth column to your cte, then wrap it in a query with rank(). find the max depth for each branch and sort descending. try SELECT *, ROW_NUMBER() OVER (ORDER BY depth DESC) FROM your_cte. works way better than plain ORDER BY for complex hierarchies.

3

You need to calculate each node’s depth and sort by that. Add a level counter to your CTE - start at 0 for the root, then increment by 1 for each child level. In your CTE’s anchor part, set Level = 0. In the recursive part, use tree.Level + 1. Then just add ORDER BY Level DESC to your SELECT. The deepest nodes will show up first but you’ll keep all the hierarchical relationships intact. Performance won’t be an issue since you’re just adding a counter and a sort to what you already have.

4

Interesting challenge! What about using a materialized path? You’d concatenate the full hierarchy path as a string, then reverse sort on that. Something like ORDER BY hierarchyPath DESC should work. How’s your current CTE performing - dealing with really deep trees?