Ordering hierarchy from recursive query results in SQL 2005

Question

I\'ve got a \'Task\' table with the following columns (the TaskOrder is for ordering the children within the scope of the parent, not the entire table):

TaskId
Pa         


        

Answer 1

Solved the problem using a variation of Mark's method, but I'm not retaining the node path in every node, so I can more easily move them around the tree. Instead I changed my 'OrderBy' column from an int to varchar(3) left-padded with zeros so I can concatenate them into a master 'OrderBy' for all the rows returned.

with tasks (TaskId, ParentTaskId, OrderBy, [Name], RowOrder) as
(
    select  parentTasks.TaskId,
            parentTasks.ParentTaskId,
            parentTasks.OrderBy,
            parentTasks.[Name],
            cast(parentTasks.OrderBy as varchar(30)) 'RowOrder'
    from    Task parentTasks
    where   ParentTaskId is null

    union all

    select  childTasks.TaskId,
            childTasks.ParentTaskId,
            childTasks.OrderBy,
            childTasks.[Name],
            cast(tasks.RowOrder + childTasks.OrderBy as varchar(30)) 'RowOrder'
    from    Task childTasks
    join    tasks
    on      childTasks.ParentTaskId = tasks.TaskId
)

select * from tasks order by RowOrder

This returns:

TaskId  ParentTaskId  OrderBy  Name                              RowOrder
---------------------------------------------------------------------------
1       NULL          001      Task One                          001
15      1             001      Task One / Task One               001001
2       NULL          002      Task Two                          002
7       2             001      Task Two / Task One               002001
14      7             001      Task Two / Task One / Task One    002001001
8       2             002      Task Two / Task Two               002002
9       8             001      Task Two / Task Two / Task One    002002001
10      8             002      Task Two / Task Two / Task Two    002002002
11      8             003      Task Two / Task Two / Task Three  002002003
3       NULL          003      Task Three                        003
4       NULL          004      Task Four                         004
13      4             001      Task Four / Task One              004001
5       NULL          005      Task Five                         005
6       NULL          006      Task Six                          006    
17      NULL          007      Task Seven                        007
18      NULL          008      Task Eight                        008
19      NULL          009      Task Nine                         009
21      19            001      Task Nine / Task One              009001
20      NULL          010      Task Ten                          010

It doesn't allow for an unlimited hierarchy (max 10 levels / max 1000 children per parent node - if I'd started the OrderBy at 0) but more than enough for my needs.