refactor duplication of SELECT inside CASE inside SELECT statement

how to refactor this select statement to remove duplication

select
    (
      case
      when (
        select my_product_int_attribute -- duplication
        from app_public.products
        where product_id = entry.product_id
      ) > 0 then 1
      when (
        select my_product_int_attribute -- duplication
        from app_public.products
        where product_id = entry.product_id
      ) = 0 then 0
      else null
      end
    )
from app_public.entries as entry
where entry.project_id = 1;

are there exists easy options without joins, maybe something like with statements that can be used inside select?

N.B.

project has many entries, entry has one product

Answer

May be use CTE instead?

;with products as (
select products.product_id, products.my_product_int_attribute 
    from app_public.products
    group by products.product_id, products.my_product_int_attribute 
)
select
(
  case
  when products.my_product_int_attribute > 0 then 1
  when products.my_product_int_attribute = 0 then 0
  else null
  end
)
from app_public.entries as entry
left join products on products.product_id = entry.product_id
where entry.project_id = 1;