SQL Server 2022

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create table mytable (
  _order varchar(20),
  item varchar(20)
);


insert into mytable values
('1234',	'001'),
('1234',	'002'),
('1235',	'001'),
('1235',	'002'),
('1235',	'003'),
('1236',	'001'),
('1237',	'001'),
('1234',	'001'),
('1234',	'002'),
('1235',	'001'),
('1235',	'002'),
('1235',	'003'),
('1236',	'001'),
('1237',	'001');
14 rows affected

with cte as (
    SELECT _order, item,
    Row_Number() OVER(PARTITION BY _order, item ORDER BY _order) as CN
    FROM mytable
)
select *
from cte
WHERE CN > 1


_order
item
CN


1234
001
2

1234
002
2

1235
001
2

1235
002
2

1235
003
2

1236
001
2

1237
001
2


with cte as (
    SELECT _order, item,
    Row_Number() OVER(PARTITION BY _order, item ORDER BY _order) as CN
    FROM mytable
)
Delete from cte WHERE cn > 1;

select * from mytable;


_order
item


1234
001

1235
001

1235
003

1237
001

1234
002

1235
002

1236
001