Question

我有下表

表格产品：

PRO_ID   PRO_Date   PRO_Price
123      1/1/2016   2000
123      2/1/2016   2500
123      3/1/2016   1500
123      5/1/2016   3000
456      1/1/2016   2000
456      2/1/2016   2500
456      3/1/2016   1500
456      5/1/2016   3000
456      6/1/2016   3500

目前使用查询：

select PRO_ID, max(PRO_DATE) as Last_PRO_Date
from
(select PRO_ID, PRO_DATE from PRODUCT where PRO_DATE<='01-JUN-2016') 
group by PRO_ID

目前获得的输出：

PRO_ID   Last_PRO_Date  
123      5/1/2016       
456      6/1/2016

但现在我想要提供第二个最后日期。

预期产出/所需产出：

PRO_ID   Last_PRO_Date   Second_Last_PRO_Date
123      5/1/2016        3/1/2016
456      6/1/2016        5/1/2016

Answer 1

您可以在没有子查询的情况下编写查询：

select PRO_ID, MAX(PRO_DATE) as Last_PRO_Date
from PRODUCT
where PRO_DATE <= '01-JUN-2016' 
group by PRO_ID;

但是，对于前两个日期，我会使用dense_rank()和聚合：

select PRO_ID,
       max(casse when seqnum = 1 then PRO_DATE end) as Last_PRO_Date,
       max(casse when seqnum = 2 then PRO_DATE end) as Second_Last_PRO_Date
from (select PRO_ID, PRO_DATE,
             dense_rank() over (partition by PRO_ID order by PRO_DATE desc) as seqnum
      from PRODUCT
      where PRO_DATE <= '01-JUN-2016' 
     ) t
group by PRO_ID;

如何使用oracle查询

1 个答案: