Tree view using SQL Query

Question

I have a regions table of which I want a tree view (table simple ordered as tree) is it possible using sql queries help is appreciated, I tried to do it using self joins but i did not get the desired result.

tree view is something like this

Indiv

• Div1
• • Zon1
• div2
• • zon2
• div3
• • zon3

EDIT:

as per Charles Bretana suggetion I tried CTE in below query and it did not give me desired result.

WITH Emp_CTE (id, ParentID, name)
AS (
SELECT id, ParentID, name
FROM eQPortal_Region
WHERE ParentID=0
UNION ALL
SELECT e.id, e.ParentID, e.name
FROM eQPortal_Region e
INNER JOIN Emp_CTE ecte ON ecte.id = e.ParentID
)
SELECT *
FROM Emp_CTE
GO

This is the result .. what went wrong ?

InDiv1

• Div1
• Div2
• Div3
• • Zon3
• • Zon2
• • zon1

Answer 1

This guy Maulik Dhorajia answers the question perfectly ...

http://maulikdhorajia.blogspot.com/2012/06/sql-server-using-ctecommon-table.html

Made a replica of the query ..

;WITH CTECompany
AS
(
    SELECT 
    ID, 
    ParentID, 
    Name , 
    0 AS HLevel,
    CAST(RIGHT(REPLICATE('_',5) +  CONVERT(VARCHAR(20),ID),20) AS VARCHAR(MAX)) AS OrderByField
FROM Region
WHERE ParentID = 0

UNION ALL

SELECT 
    C.ID, 
    C.ParentID, 
    C.Name , 
    (CTE.HLevel + 1) AS HLevel,
    CTE.OrderByField + CAST(RIGHT(REPLICATE('_',5) +  CONVERT(VARCHAR(20),C.ID),20) AS VARCHAR(MAX)) AS OrderByField
FROM Region C
INNER JOIN CTECompany CTE ON CTE.ID = C.ParentID
WHERE C.ParentID IS NOT NULL


)

-- Working Example
SELECT 
ID
, ParentID
, HLevel
, Name
, (REPLICATE( '----' , HLevel ) + Name) AS Hierachy
FROM CTECompany
ORDER BY OrderByField

Answer 2

See the following sample SQL script:

DECLARE @lV NCHAR(1)=NCHAR(9474),@lR NCHAR(1)=NCHAR(9500),@lU NCHAR(1)=NCHAR(9492),@spc NCHAR(1)='　';
WITH data AS(SELECT * FROM(VALUES(1,'0','In Div1',1),(2,'1','Div1',1),(3,'2','zon1',1),(4,'1','Div2',2),(5,'1','Div3',3),(6,'4','Zon2',1),(7,'5','Zon3',1))t([ID],[ParentID],[Name],[SeqOrder])
),d_root AS(SELECT CAST('/'AS NVARCHAR(MAX))[n_path],* FROM data WHERE ParentID='0'
),d_cte AS(SELECT b.n_path+CAST(ROW_NUMBER()OVER(ORDER BY a.ID)AS NVARCHAR(MAX))+'/'[n_path],a.* FROM data a INNER JOIN d_root b ON a.ParentID=b.ID UNION ALL SELECT b.n_path+CAST(ROW_NUMBER()OVER(ORDER BY a.ID)AS NVARCHAR(MAX))+'/'[n_path],a.* FROM data A INNER JOIN d_cte b ON a.ParentID=b.ID
),Tree_BASE AS (SELECT CAST(n_path AS HIERARCHYID)[h_id],* FROM d_root UNION ALL SELECT CAST(n_path AS HIERARCHYID)[h_id],* FROM d_cte
),cte_o AS(SELECT a.h_id,CASE WHEN EXISTS(SELECT * FROM Tree_BASE WHERE h_id>b.h_id AND h_id.GetAncestor(1)=b.h_id.GetAncestor(1))THEN @lV ELSE @spc END[t_l] FROM Tree_BASE a INNER JOIN Tree_BASE b ON a.h_id.IsDescendantOf(b.h_id)=1 AND NOT b.h_id=HIERARCHYID::GetRoot()
),cte_m AS(SELECT x.*,(SELECT t_l+'' FROM cte_o WHERE h_id=x.h_id FOR XML PATH(''))[b_tree] FROM Tree_BASE x
),cte_h AS(SELECT ISNULL(LEFT(b_tree,LEN(b_tree)-1)+CASE WHEN EXISTS(SELECT * FROM Tree_BASE WHERE h_id>a.h_id AND h_id.GetAncestor(1)=a.h_id.GetAncestor(1))THEN @lR ELSE @lU END,'')+' '+RTRIM(Name) [TreeV],a.h_id FROM cte_m a
)SELECT b.TreeV,ROW_NUMBER()OVER(ORDER BY a.h_id ASC)[row_id]FROM Tree_BASE a INNER JOIN cte_h b ON a.h_id=b.h_id ORDER BY row_id