SQL Building Pathway using With Union in SQL Server - sql

Question

This is SQL Server Question
I have a set of categories, and their relationship results in nested categories.
I want to build a pathway keeping the relationship and build the SEF urls. Here is what I am looking for:
Category table:
ID, Name
1, Root
2, Cat1
3, Cat2
4, Cat1.1
5, Cat1.2
6, Cat2.1
7, Cat2,2
CategoryChild table: ParentCategoryID, ChildCategoryID
1, 2
1, 3
2, 4
2, 5
3, 6
3, 7
It is an unlimited nested structure. Here is what I am doing (I know its wrong but want something like this):
WITH MenuItems
AS (
SELECT
CAST((ItemPath) AS VARCHAR(1000)) AS 'ItemPath',
CategoryID, Category, ChildID
FROM #Mapping
WHERE CategoryID = 1
UNION ALL
SELECT
CAST((items.ItemPath + '-/' + MenuItem.Category) AS VARCHAR(1000)) AS 'ItemPath',
MenuItem.CategoryID, MenuItem.Category, MenuItem.ChildID
FROM #Mapping AS MenuItem
JOIN MenuItems AS items
ON items.ChildID = MenuItem.CategoryID
)
select * from MenuItems
It gives me something like this:
root--------|1---|root---|2
root--------|1---|root---|3
root/Cat2---|3---|Cat2---|6
root/Cat2---|3---|Cat2---|7
root/Cat1---|2---|Cat1---|4
root/Cat1---|2---|Cat1---|5
So ideally the path should be like this:
root/parent/child (and so on)!

Answer 1

I'm not sure if this is what you're looking for but I've played with recursive cte's in the past and so this might be helpful in building the items path.
NOTE: I've included additional information like the Root Id and Level for each item, so that you can change the ordering of the output.
declare #Category table (Id int, Name varchar(10))
insert into #Category values (1, 'Root'),(2, 'Cat1'), (3, 'Cat2'), (4, 'Cat1.1'), (5, 'Cat1.2'), (6, 'Cat2.1'), (7, 'Cat2.2')
declare #CategoryChild table (ParentCategoryID int, ChildCategoryID int)
insert into #CategoryChild values (1, 2), (1, 3), (2, 4), (2, 5), (3, 6), (3, 7)
;with cte as
(
-- root part
select
ccParent.ChildCategoryID Id,
ccParent.ParentCategoryID ParentId,
c.Name Name,
CAST(parentCategory.Name + '/' + c.Name as varchar(1000)) as Path,
ccParent.ChildCategoryID Root,
0 as Level
from
#CategoryChild ccParent
inner join
#Category c on c.Id = ccParent.ChildCategoryID
inner join
#Category parentCategory on parentCategory.Id = ccParent.ParentCategoryID
where
ccParent.ParentCategoryID = 1
union all
-- recursive part
select
ccChild.ChildCategoryID Id,
ccChild.ParentCategoryID ParentId,
c.Name Name,
CAST((cte.Path + '/' + c.Name) as varchar(1000)) as Path,
cte.Root Root,
cte.Level + 1 as Level
from
#CategoryChild ccChild
inner join
#Category c on c.Id = ccChild.ChildCategoryID
inner join
cte on cte.Id = ccChild.ParentCategoryID
)
select cte.Path
from cte
order by cte.Root, cte.Level
Running the above within my environment gives the following results
Root/Cat1
Root/Cat1/Cat1.1
Root/Cat1/Cat1.2
Root/Cat2
Root/Cat2/Cat2.1
Root/Cat2/Cat2.2
If you were looking to include the Root category in your result set as a standalone item then you can change the first part of the cte to hard code the select of the root item.
;with cte as
(
-- root part
select
c.Id Id,
null ParentId,
c.Name Name,
CAST(c.Name as varchar(1000)) as Path,
c.Id Root,
0 as Level
from
#Category c
where
c.Name = 'Root'
union all
... same as before
Giving the follow
Root
Root/Cat1
Root/Cat1/Cat1.1
Root/Cat1/Cat1.2
Root/Cat2
Root/Cat2/Cat2.1
Root/Cat2/Cat2.2