SQL Server 2016

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12 rows affected

;with cte as (
SELECT *,row_number() over (partition by Customer_ID order by Customer_ID) as Number
FROM computers
),
cte2 as (
select  DISTINCT
        c.Customer_ID,
        c.Computer_Name,
        'Computer_Name_' + cast(Number as varchar(1)) as Computer
from cte as c
),
cte_dist2 as (
select distinct 
        Customer_ID
from computers
),
cte3 as (
select c.Customer_ID,
        c.Computer_OS,
        'Computer_OS_' + cast(Number as varchar(1)) as OS
from cte as c
)
select  DISTINCT
        cd2.Customer_ID,
        MAX(IIF(c2.Computer='Computer_Name_1',c2.Computer_Name,NULL)) as Computer_Name_1,
        MAX(IIF(c3.OS='Computer_OS_1',c3.Computer_OS,NULL)) as Computer_OS_1,
        MAX(IIF(c2.Computer='Computer_Name_2',c2.Computer_Name,NULL)) as Computer_Name_2,
        MAX(IIF(c3.OS='Computer_OS_2',c3.Computer_OS,NULL)) as Computer_OS_2,
        MAX(IIF(c2.Computer='Computer_Name_3',c2.Computer_Name,NULL)) as Computer_Name_3,
        MAX(IIF(c3.OS='Computer_OS_3',c3.Computer_OS,NULL)) as Computer_OS_3,
        MAX(IIF(c2.Computer='Computer_Name_4',c2.Computer_Name,NULL)) as Computer_Name_4,
        MAX(IIF(c3.OS='Computer_OS_4',c3.Computer_OS,NULL)) as Computer_OS_4,
        MAX(IIF(c2.Computer='Computer_Name_5',c2.Computer_Name,NULL)) as Computer_Name_5,
        MAX(IIF(c3.OS='Computer_OS_5',c3.Computer_OS,NULL)) as Computer_OS_5
from cte_dist2 as cd2
    inner join cte2 as c2 ON cd2.Customer_ID = c2.Customer_ID
    inner join cte3 as c3 ON cd2.Customer_ID = c3.Customer_ID
group by cd2.Customer_ID

Customer_ID	Computer_Name_1	Computer_OS_1	Computer_Name_2	Computer_OS_2	Computer_Name_3	Computer_OS_3	Computer_Name_4	Computer_OS_4	Computer_Name_5	Computer_OS_5
15001	DESKTOP-JKVB	WINDOWS 7	DESKTOP-SKVB	WINDOWS 2012R2	null	null	null	null	null	null
15002	PC-JKVB45	WINDOWS VISTA	JOHN-PC	WINDOWS 10	SERVER-DC	WINDOWS 7	DATA-PC	WINDOWS 2016	PC-BACKOFFICE	WINDOWS 2008R2
15003	DESKTOP-XPBACK	WINDOWS 7	PC-HDFU	WINDOWS 2012R2	DESKTOP-NO2	WINDOWS 10	null	null	null	null
15004	SERVER-DHCP	WINDOWS 7	DESKTOP-NO1	WINDOWS 2012R2	null	null	null	null	null	null

Warning: Null value is eliminated by an aggregate or other SET operation.