SQL Server 2019

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select @@version;


(No column name)


Microsoft SQL Server 2019 (RTM-CU3) (KB4538853) - 15.0.4023.6 (X64) 
 Mar  4 2020 00:59:26 
 Copyright (C) 2019 Microsoft Corporation
 Express Edition (64-bit) on Windows Server 2019 Standard 10.0 <X64> (Build 17763: ) (Hypervisor)



create table #t(type varchar(100), unite varchar(100), Item_ID int)
insert into #t select 'First',  NULL, 1
insert into #t select 'First',  NULL, 2
insert into #t select 'First',  NULL, 3
insert into #t select 'Second', 'Unite1', 1
insert into #t select 'Second', 'Unite2', 2
insert into #t select 'Second', NULL, 3

select * from #t


type
unite
Item_ID


First
null
1

First
null
2

First
null
3

Second
Unite1
1

Second
Unite2
2

Second
null
3


DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX);

SET @cols = STUFF((select distinct ', 
            MAX(CASE WHEN [Item_ID]=''' + CAST([Item_ID] as varchar(10)) + ''' THEN unite ELSE NULL END) AS [Item_unite_ID' + CAST([Item_ID] as varchar(10)) + ']'
            /*---------------You can add other columns here similar to above--------------*/
            FROM #t 
            FOR XML PATH(''),type).value('.','varchar(max)'),1,2,'')
SET @query = 'SELECT [type], ' + @Cols + '  FROM #t group by [type]' 

print (@query)
exec(@query)


type
Item_unite_ID1
Item_unite_ID2
Item_unite_ID3


First
null
null
null

Second
Unite1
Unite2
null


SELECT [type], 
            MAX(CASE WHEN [Item_ID]='1' THEN unite ELSE NULL END) AS [Item_unite_ID1], 
            MAX(CASE WHEN [Item_ID]='2' THEN unite ELSE NULL END) AS [Item_unite_ID2], 
            MAX(CASE WHEN [Item_ID]='3' THEN unite ELSE NULL END) AS [Item_unite_ID3]  FROM #t group by [type]
Warning: Null value is eliminated by an aggregate or other SET operation.
type	unite	Item_ID
First	null	1
First	null	2
First	null	3
Second	Unite1	1
Second	Unite2	2
Second	null	3