Tree view using SQL Query

问题

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

回答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

来源：https://stackoverflow.com/questions/18631194/tree-view-using-sql-query

标签

sql

join

treeview

common-table-expression

self