Sort hierarchical table CTE query - tsql

Question

How I can sort a hierarchical table with CTE query ?
sample table :
|ID|Name |ParentID|
| 0| |-1 |
| 1|1 |0 |
| 2|2 |0 |
| 3|1-1 |1 |
| 4|1-2 |1 |
| 5|2-1 |2 |
| 6|2-2 |2 |
| 7|2-1-1 |5 |
and my favorite result is :
|ID|Name |ParentID|Level
| 0| |-1 |0
| 1|1 |0 |1
| 3|1-1 |1 |2
| 4|1-2 |1 |2
| 2|2 |0 |1
| 5|2-1 |2 |2
| 7|2-1-1 |5 |3
| 6|2-2 |2 |2
another Sample :
an other sample :
|ID|Name |ParentID|
| 0| |-1 |
| 1|Book |0 |
| 2|App |0 |
| 3|C# |1 |
| 4|VB.NET |1 |
| 5|Office |2 |
| 6|PhotoShop |2 |
| 7|Word |5 |
and my favorite result is :
|ID|Name |ParentID|Level
| 0| |-1 |0
| 1|Book |0 |1
| 3|C# |1 |2
| 4|VB.NET |1 |2
| 2|App |0 |1
| 5|Office |2 |2
| 7|Word |5 |3
| 6|PhotoShop |2 |2

Answer 1

The hierarchyid datatype is able to represent hierarchical data, and already has the desired sorting order. If you can't replace your ParentID column, then you can convert to it on the fly:
(Most of this script is data setup, the actual answer is quite small)
declare #t table (ID int not null,Name varchar(10) not null,ParentID int not null)
insert into #t(ID,Name,ParentID)
select 0,'' ,-1 union all
select 1,'Book' ,0 union all
select 2,'App' ,0 union all
select 3,'C#' ,1 union all
select 4,'VB.NET' ,1 union all
select 5,'Office' ,2 union all
select 6,'PhotoShop' ,2 union all
select 7,'Word' ,5
;With Sensible as (
select ID,Name,NULLIF(ParentID,-1) as ParentID
from #t
), Paths as (
select ID,CONVERT(hierarchyid,'/' + CONVERT(varchar(10),ID) + '/') as Pth
from Sensible where ParentID is null
union all
select s.ID,CONVERT(hierarchyid,p.Pth.ToString() + CONVERT(varchar(10),s.ID) + '/')
from Sensible s inner join Paths p on s.ParentID = p.ID
)
select
*
from
Sensible s
inner join
Paths p
on
s.ID = p.ID
order by p.Pth

Answer 2

ORDER BY Name should work as desired:
WITH CTE
AS(
SELECT parent.*, 0 AS Level
FROM #table parent
WHERE parent.ID = 0
UNION ALL
SELECT parent.*, Level+1
FROM #table parent
INNER JOIN CTE prev ON parent.ParentID = prev.ID
)
SELECT * FROM CTE
ORDER BY Name
Here's your sample data(add it next time yourself):
declare #table table(ID int,Name varchar(10),ParentID int);
insert into #table values(0,'',-1);
insert into #table values(1,'1',0);
insert into #table values(2,'2',0);
insert into #table values(3,'1-1',1);
insert into #table values(4,'1-2',1);
insert into #table values(5,'2-1',2);
insert into #table values(6,'2-2',2);
insert into #table values(7,'2-1-1',5);
Result:
ID Name ParentID Level
0 -1 0
1 1 0 1
3 1-1 1 2
4 1-2 1 2
2 2 0 1
5 2-1 2 2
7 2-1-1 5 3
6 2-2 2 2