There is a 1-to-1 relationship between ids and items.
with item_ids as (
select 1 as id
union select 2
union select 3
union select 4
union select 5
union select 6
)
select items.*
from item_ids
left join items on items.id = item_ids.id
select *
from items
where id in (1, 2, 3, 4, 5, 6)