Update count column from data in another table

Question

In my DB I have two tables Items(Id, ..., ToatlViews int) and ItemViews (id, ItemId, Timestamp)

In ItemViews table I store all views of an item as they come to the s

Answer 1

Same but different:

declare @productId int = 24;
declare @classificationTypeId int = 86;

update s
set CounterByProductAndClassificationType = row_num
from Samples s
join
(
    select row_number() over (order by (select Id)) row_num, Id
    from Samples
    where 
        ProductId = @productId and
        ClassificationTypeId = @classificationTypeId
) s_row on s.Id = s_row.Id