因此，我的业务需求是每天吸引前30名客户（有关系），并且每个客户每周只能被选择一次。因此，我进行了三个查询，每个查询都相同（很好），但是我在理论上有疑问。
1）第一种方法是，当我有两个CTE并在表达式中从这两个组中选择TOP 30时，这是设置操作（EXCEPT）的一部分，但是-据我所知-我们不应该使用order在设定操作中，对吗？顺便说一句，顺便说一句
WITH A
AS (select dbo.customerentities.customer_id, first_name, last_name, tel,
sale.sum_sale
from dbo.CustomerSubscriptions ---check for client's subscriptions
left join dbo.CustomerEntities on dbo.CustomerSubscriptions.customer_id =
dbo.CustomerEntities.customer_id
left join (select customer_id, sum (sale) as sum_sale, from dbo.OrderTable
where sale_date between CONVERT(DATE, getdate() - 2) and convert(date,
getdate() - 1) group by customer_id) as sale on CustomerEntities.customer_id
= sale.customer_id
where not sale.sum_sale is null),
B
AS (select dbo.customerentities.customer_id, first_name, last_name, tel,
sale.sum_sale
from dbo.CustomerSubscriptions ---check for client's subscriptions
left join dbo.CustomerEntities on dbo.CustomerSubscriptions.customer_id =
dbo.CustomerEntities.customer_id
left join (select customer_id, sum (sale) as sum_sale, from dbo.OrderTable
where sale_date between CONVERT(DATE, getdate() - 1) and convert(date,
getdate()) group by customer_id) as sale on CustomerEntities.customer_id
= sale.customer_id
where not sale.sum_sale is null)
select *from B where customer_id in
(select top 30 with ties customer_id from B order by sale desc
except
select top 30 with ties customer_id from A order by sale desc)
order by sale desc
2）第二个几乎相同，但是我决定选择CTE级别的前30名，但是再一次-CTE是关系，对吗？所以我们不应该在关系中使用order by吗？否则，它会起作用。
WITH A
AS (select top 30 with ties dbo.customerentities.customer_id, first_name,
last_name, tel,
sale.sum_sale
from dbo.CustomerSubscriptions ---check for client's subscriptions
left join dbo.CustomerEntities on dbo.CustomerSubscriptions.customer_id =
dbo.CustomerEntities.customer_id
left join (select customer_id, sum (sale) as sum_sale, from dbo.OrderTable
where sale_date between CONVERT(DATE, getdate() - 2) and convert(date,
getdate() - 1) group by customer_id) as sale on CustomerEntities.customer_id
= sale.customer_id
where not sale.sum_sale is null
order by sale desc),
B
AS (select top 30 with ties dbo.customerentities.customer_id, first_name,
last_name, tel,
sale.sum_sale
from dbo.CustomerSubscriptions ---check for client's subscriptions
left join dbo.CustomerEntities on dbo.CustomerSubscriptions.customer_id =
dbo.CustomerEntities.customer_id
left join (select customer_id, sum (sale) as sum_sale, from dbo.OrderTable
where sale_date between CONVERT(DATE, getdate() - 1) and convert(date,
getdate()) group by customer_id) as sale on CustomerEntities.customer_id
= sale.customer_id
where not sale.sum_sale is null
order by sale desc)
select *from B where customer_id in
(select customer_id from B
except
select customer_id from A )
order by sale desc
3）第三种方法是最差的一种，但我对此毫无疑问。
select A.customer_id, A.first_name, A.last_name, A.tel, A.sum_sale
from (select top 30 with ties dbo.customerentities.customer_id, first_name,
last_name, tel,
sale.sum_sale
from dbo.CustomerSubscriptions ---check for client's subscriptions
left join dbo.CustomerEntities on dbo.CustomerSubscriptions.customer_id =
dbo.CustomerEntities.customer_id
left join (select customer_id, sum (sale) as sum_sale, from dbo.OrderTable
where sale_date between CONVERT(DATE, getdate() - 1) and convert(date,
getdate()) group by customer_id) as sale on CustomerEntities.customer_id
= sale.customer_id
where not sale.sum_sale is null
order by sale desc) as A
left join (select top 30 with ties dbo.customerentities.customer_id,
first_name,
last_name, tel,
sale.sum_sale
from dbo.CustomerSubscriptions ---check for client's subscriptions
left join dbo.CustomerEntities on dbo.CustomerSubscriptions.customer_id =
dbo.CustomerEntities.customer_id
left join (select customer_id, sum (sale) as sum_sale, from dbo.OrderTable
where sale_date between CONVERT(DATE, getdate() - 2) and convert(date,
getdate() - 1) group by customer_id) as sale on CustomerEntities.customer_id
= sale.customer_id
where not sale.sum_sale is null
order by sale desc) as B on A.customer_id = B.customer_id
where B.customer_id is null --- to exclude customers which already received
--- bonus day earlier
order by sale desc
所以我的问题是-我应该使用第三种方法，还是可以通过CTE /设置操作轻松地使用顶级订单？