SQL Server : pivot a single column with fixed number or columns - sql-server

Question

I have this simple query that brings the siblings of a given item.
select
PC.SKU
from
ProdC PC
where
Parent_ID in (select Parent_ID
from ProdC
where SKU = 4536)
and ParentFlag <> 'P'
and SKU <> 4536
I'd like to display up to 6 siblings horizontally. So it would look something like this:
Sib1 Sib2 Sib3 Sib4 Sib5 Sib6
=============================================
4532 4539 4548 4552 4561 4562
3512 3536
5632 5636 5640
Now each of these row are for a different item. some parent have 2 child, some have up to 8 but I only want to show 6 max. There's a priority column for the children. I can sort it by that column desc to get the 6 newest child.
Any help appreciated.

Answer 1

I have a table in my test database with records with multiple child records for each parent record, created the following query to only get the top 6 child records, but it only picks the immediate child records, if you have another level of children records then you probably need to look into recursive CTE etc.
;WITH X AS
(
Select *
,ROW_NUMBER() OVER (PARTITION BY Parent_ID ORDER BY ID) rn
from TableName
),
Y AS (
Select * , 'Sib' + Cast(rn AS Varchar(10)) Sibs
FROM X
Where rn < 7
)
Select *
from
(
Select Parent_ID , Sibs , ID
FROM Y
) a
PIVOT (MAX(ID)
FOR Sibs
IN (Sib1,Sib2,Sib3,Sib4,Sib5,Sib6))p
Result Set
+----------+------+------+------+------+-------+------+
| ParentID | Sib1 | Sib2 | Sib3 | Sib4 | Sib5 | Sib6 |
+----------+------+------+------+------+-------+------+
| 0 | 0 | 139 | 258 | 266 | 285 | 500 |
| 139 | 140 | 141 | 142 | 143 | 144 | 162 |
| 142 | 5062 | 5063 | NULL | NULL | NULL | NULL |
| 143 | 5041 | 5042 | 5043 | 5044 | 5045 | 5046 |
| 144 | 5050 | 5051 | 5052 | 5053 | 5054 | 5055 |
| 258 | 5823 | 5824 | 5825 | 5826 | 11269 | NULL |
| 266 | 5822 | 5912 | 5913 | 5914 | 5915 | 5916 |
| 285 | 2139 | 3855 | 4172 | 4173 | NULL | NULL |
+----------+------+------+------+------+-------+------+
EDIT
After you have provided some sample data your query should look something like..
;WITH X AS
(
Select *
,ROW_NUMBER() OVER (PARTITION BY Parent_Sku ORDER BY sku) rn
from #ProdC
),
Y AS (
Select * , 'Sib' + ISNULL(NULLIF(Cast(rn -1 AS Varchar(10)), '0'),'') Sibs
FROM X
Where rn < 8
)
Select Sib1,Sib2,Sib3,Sib4,Sib5,Sib6
from
(
Select Parent_Sku , Sibs , sku
FROM Y
) a
PIVOT (MAX(sku)
FOR Sibs
IN (Sib,Sib1,Sib2,Sib3,Sib4,Sib5,Sib6,Sib7))p
Result set
| Sib1 | Sib2 | Sib3 | Sib4 | Sib5 | Sib6 |
|------|------|------|--------|--------|--------|
| 4532 | 4536 | 4539 | 4548 | 4552 | (null) |
| 3512 | 3536 | 4561 | 4562 | (null) | (null) |
| 5632 | 5636 | 5640 | (null) | (null) | (null) |