SQL query to get multihierarchy items - sql

Question

in my SQL Table i have following data
ID Level Description Code MasterID
1 1 Cars AD0 NULL
2 1 Trucks JF1 NULL
3 1 Items YU2 NULL
4 2 New Cars AS3 1
5 2 Used Cars TG4 1
6 2 Car parts UJ5 1
7 2 New trucks OL6 2
8 2 Used trucks PL7 2
9 2 Truck parts KJL8 2
10 2 Factory stuff UY9 3
11 2 Custom stuff RT10 3
12 3 Toyota 6YH11 4
13 3 BMW 9OKH12 4
14 3 VW 13 5
15 3 Tiers Type I J14 6
16 3 Tiers Type II J15 6
17 3 Tiers Type III ADS16 9
18 3 Seats SA17 6
19 3 Doors UU18 6
20 3 Lights 9OL19 6
21 4 Left light GH20 20
22 4 Right light H21 20
23 4 Left door JHJ22 19
24 4 Michelin UY23 16
25 4 Vredestein GTF24 17
26 4 Dunlop 25 15
My achievement is to get all hierarchy data for each single item. For Exmaple, the outpu should look like as following
ID Level Description Code MasterId1 Description1 MasterId2 Description2 MasterId3 Description3
24 4 Michelin UY23 16 Tiers Type II 6 Car Parts 1 Cars
.
.
19 3 Doors UU18 6 Car Parts 1 Cars NULL NULL
.
.
10 2 Factory Stuff UY9 3 Items NULL NULL NULL NULL
.
.
3 1 Items NULL NULL NULL NULL NULL NULL NULL
.
.
If somebody can help or give an advise how to achieve this?

Answer 1

This is not dynamic but it could be pretty easily.
Using a recursive cte you can get the hierarchy for the entire table and self join a few times to get the table structure you want.
;WITH cte AS
(
SELECT *, ID AS [RootID], 1 AS [MasterLevel] FROM Table1
UNION ALL
SELECT t1.*, cte.[RootID], cte.[MasterLevel] + 1 FROM Table1 t1
JOIN cte ON t1.ID = cte.MasterID
)
SELECT r.ID, r.[Level], r.[Description], r.[Code],
m1.ID AS MasterId1, m1.[Description] AS Description1,
m2.ID AS MasterId2, m1.[Description] AS Description2,
m3.ID AS MasterId3, m1.[Description] AS Description3
FROM cte r
LEFT JOIN cte m1 ON m1.[RootID] = r.[RootID] AND m1.MasterLevel = 2
LEFT JOIN cte m2 ON m2.[RootID] = r.[RootID] AND m2.MasterLevel = 3
LEFT JOIN cte m3 ON m3.[RootID] = r.[RootID] AND m3.MasterLevel = 4
WHERE r.MasterLevel = 1
ORDER BY r.RootID DESC, r.MasterLevel
This would build a dynamic sql to get master and desciption fields based on the maximum Level value. or you could define how many levels you want to see by changing the #MaxLevel
DECLARE #Sql VARCHAR(MAX) = '',
#SelectSql VARCHAR(MAX) = '',
#JoinSql VARCHAR(MAX) = '',
#MaxLevel INT,
#idx INT = 1
SET #MaxLevel = (SELECT MAX([Level]) FROM Table1)
WHILE #idx < #MaxLevel
BEGIN
SET #SelectSql = #SelectSql + REPLACE(', m<index>.ID AS MasterId<index>, m<index>.[Description] AS Description<index> ', '<index>', #idx)
SET #JoinSql = #JoinSql + REPLACE(' LEFT JOIN cte m<index> ON m<index>.[RootID] = r.[RootID] AND m<index>.MasterLevel = <index> ', '<index>', #idx)
SET #idx = #idx + 1
END
SET #Sql = '
;WITH cte AS
(
SELECT *, ID AS [RootID], 0 AS [MasterLevel] FROM Table1
UNION ALL
SELECT t1.*, cte.[RootID], cte.[MasterLevel] + 1 FROM Table1 t1
JOIN cte ON t1.ID = cte.MasterID
)
SELECT r.ID, r.[Level], r.[Description], r.[Code]' + #SelectSql
+ 'FROM cte r ' + #JoinSql
+ 'WHERE r.MasterLevel = 0
ORDER BY r.RootID DESC, r.MasterLevel'
EXEC(#Sql)