甲骨文 sql 问题 98

Question

我需要显示最近订单的日期以及与该订单关联的订单 ID，但我似乎无法弄清楚如何只 return 最近订单的唯一订单 ID命令。这是我目前所拥有的：

select  custlastname || ', ' || custfirstname as Contact_Name,
max(orderdate), orderid
from customer inner join custorder
on customer.customerid = custorder.customerid
where state = 'OH' and companyname is not null  
group by custlastname, custfirstname, orderid
order by custlastname, custfirstname;

这 return 有 10 个结果，但我只想要具有该特定订单 ID 的最新订单？

Answer 1

您可以使用 row_number():

select  custlastname || ', ' || custfirstname as Contact_Name, orderid
from customer c inner join
     (select o.*,
             row_number() over (partition by customerid order by orderdate desc) as seqnum
      from custorder o
     ) o
     on c.customerid = o.customerid and seqnum = 1
where state = 'OH' and companyname is not null  ;
order by custlastname, custfirstname;

甲骨文 sql 问题 98

oracle sql question98

sql

oracle

greatest-n-per-group