sql - 在 SELECT 语句中的 CASE 中重构 SELECT 的重复

Question

如何重构此 select 语句以删除重复

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;

是否存在没有连接的简单选项，也许像 with 语句可以在 select 中使用？

注意

项目有多个条目，条目有一个产品

Answer 1

可以改用 CTE 吗？

;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;