SQL Row_number() 重复

Question

我在处理以下代码时遇到了一些问题。我正在处理一个顶级购物篮问题，我正在尝试计算每笔交易应该只有 4 件商品的购物篮组合的数量。下面的代码运行良好，但是当一笔交易额外购买了 4 件商品（或更多）时，它不会被计入 combined_basket 步骤。

With RowNums as (
select 
edw_transaction_id, row_number() over (partition by edw_transaction_id     order by article_name) as row_id, article_name
from thing1
 ),


 BasketItems as (
select a.edw_transaction_id, a.article_name as _1, b.article_name as_2,c.article_name as _3,d.article_name as _4
from (select edw_transaction_id,article_name from RowNums where row_id =1) a
join (select edw_transaction_id,article_name from RowNums where row_id =2) b
on a.edw_transaction_id = b.edw_transaction_id
join (select edw_transaction_id,article_name from RowNums where row_id =3) c
on a.edw_transaction_id = c.edw_transaction_id
join (select edw_transaction_id,article_name from RowNums where row_id =4) d
on a.edw_transaction_id = d.edw_transaction_id
),

combined_basket as (
select count(*) as basket_count, _1 as basket_item1,_2 as basket_item2,_3 as basket_item3,_4 as basket_item4
from BasketItems 
group by 2,3,4,5
order by 1 desc
)

select * 
from combined_basket
order by 1 desc
limit 10

BasketItems 的输出看起来像这样：

Trans Id    Row_num     Article_Name
6368773827  1   Apples
6368773827  2   Oranges
6368773827  3   Cheese
6368773827  4   Egg
6368774403  1   Apple
6368774403  2   Egg
6368774403  3   Cake
6368774403  4   Salad
6368774403  5   Egg
6368774403  6   Apple
6368774403  7   Lemon
6368774403  8   Burger

从上面的代码可以看出，它只会计算前 4 项，其余的（对于每笔交易）。有没有一种方法可以在超过 4 时重复 row_number 函数，或者是否有其他方法可以解决这个问题，以便计算每笔 4 的交易？

交易的期望结果是每件商品都标记为 1 到 4。

Answer 1

你可以添加一个数学函数，即Row_number % 4。即使没有分区也能解决问题：

row_number() over (order by article_name) % 4 as row_id

不过，我不是 100% 确定 % 作为符号是否存在于 MySQL 中。如果没有，就找模块化划分。

SQL Row_number() 重复

SQL Row_number() Repeat

mysql

sql

relational-database

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