SQL Server 2019

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create table t (
id int primary key,
version int,
item_no int not null,
notes varchar(255)
);
insert into t values
(1, null, 31, null),
(2, 1, 31, 'tasty'),
(3, 2, 31, 'kinda tasty'),
(4, null, 32, null),
(5, 1, 32, 'meh'),
(6, 2, 32, 'alright'),
(7, 3, 32, 'fabulous'),
(8, null, 33, 'ambivalent'),
(9, 1, 33, 'gross'),
(10, 2, 33, 'puke');
10 rows affected

update t set 
notes = (
   select top 1 s.notes 
   from t s 
   where s.item_no = t.item_no 
   order by version desc
) where version is null and notes is null
2 rows affected

select * from t;


id
version
item_no
notes


1
null
31
kinda tasty

2
1
31
tasty

3
2
31
kinda tasty

4
null
32
fabulous

5
1
32
meh

6
2
32
alright

7
3
32
fabulous

8
null
33
ambivalent

9
1
33
gross

10
2
33
puke


select @@version;


(No column name)


Microsoft SQL Server 2019 (RTM-CU16) (KB5011644) - 15.0.4223.1 (X64) 
 Apr 11 2022 16:24:07 
 Copyright (C) 2019 Microsoft Corporation
 Express Edition (64-bit) on Windows Server 2019 Standard 10.0 <X64> (Build 17763: ) (Hypervisor)

id	version	item_no	notes
1	null	31	kinda tasty
2	1	31	tasty
3	2	31	kinda tasty
4	null	32	fabulous
5	1	32	meh
6	2	32	alright
7	3	32	fabulous
8	null	33	ambivalent
9	1	33	gross
10	2	33	puke