SQL: 如何处理NULL和PARTITION BY？

Question

我有一个问题，如果你不介意的话。因此，假设我这里有这种 table – 产品（2000 年按季度销售的数量，只有同一产品和季度（不同日期）有多个条目）：

product	quarter	amount sold
Jeans	1	20
Jeans	2	40
Jeans	3	60
Jeans	4	5
Skirt	1	10
Skirt	2	5
Skirt	3	30
Blouse	1	15
Blouse	2	40
Blouse	3	60
Blouse	4	15

我想重新介绍如下：

product	quarter1	quarter2	quarter3	quarter4
Jeans	20	40	60	5
Skirt	10	5	30	Null
Blouse	15	40	60	15

我决定用分区来做（因为它并不是那么简单，同一产品的同一季度有不同的行，但销售量不同，这就是为什么它是总和（amount_sold），但我希望你明白了）：

WITH quater_sales as(
SELECT DISTINCT pro.product, pro.quarter, to_char (sum(pro.amount_sold) OVER (PARTITION BY pro.product, pro.quarter)) AS quater
FROM products pro
ORDER BY pro.pro.product)
SELECT quater_sales.prod_product, quater_sales.quater AS "Q1", qu2.quater AS "Q2", qu3.quater AS "Q3", qu4.quater AS "Q4"
FROM quater_sales
 JOIN quater_sales qu2 ON quater_sales.prod_subcategory=qu2.prod_subcategory
 JOIN quater_sales qu3 ON quater_sales.prod_subcategory=qu3.prod_subcategory
 JOIN quater_sales qu4 ON quater_sales.prod_subcategory=qu4.prod_subcategory
WHERE quater_sales.calendar_quarter_number=1 and qu2.calendar_quarter_number=2 and qu3.calendar_quarter_number=3 and qu4.calendar_quarter_number=4

问题出在分区上（或者可能是select的情况），4个季度都没有售出的产品就被丢弃了。我最终得到的基本上是这样的：

product	quarter1	quarter2	quarter3	quarter4
Jeans	20	40	60	5
Blouse	15	40	60	15

那么如何让“裙子”也出现在那里呢？我对此有点困惑。

Answer 1

您是否考虑过使用 PIVOT 语句？

WITH
    quarter_sales (product, quarter, amount_sold)
    AS
        (SELECT 'Jeans', 1, 20 FROM DUAL
         UNION ALL
         SELECT 'Jeans', 2, 40 FROM DUAL
         UNION ALL
         SELECT 'Jeans', 3, 60 FROM DUAL
         UNION ALL
         SELECT 'Jeans', 4, 5 FROM DUAL
         UNION ALL
         SELECT 'Skirt', 1, 10 FROM DUAL
         UNION ALL
         SELECT 'Skirt', 2, 5 FROM DUAL
         UNION ALL
         SELECT 'Skirt', 3, 30 FROM DUAL
         UNION ALL
         SELECT 'Blouse', 1, 15 FROM DUAL
         UNION ALL
         SELECT 'Blouse', 2, 40 FROM DUAL
         UNION ALL
         SELECT 'Blouse', 3, 60 FROM DUAL
         UNION ALL
         SELECT 'Blouse', 4, 15 FROM DUAL)
SELECT *
  FROM (SELECT *
          FROM quarter_sales qs)
       PIVOT (SUM (amount_sold)
             FOR quarter
             IN (1 AS quarter1, 2 AS quarter2, 3 AS quarter3, 4 AS quarter4));


   PRODUCT    QUARTER1    QUARTER2    QUARTER3    QUARTER4
__________ ___________ ___________ ___________ ___________
Blouse              15          40          60          15
Jeans               20          40          60           5
Skirt               10           5          30

Answer 2

尝试转轴。这就是你在 sql

中的转向方式

declare @tmp as table(product varchar(20),quarter int,[amount sold] int);

insert into @tmp values
('Jeans',   1,  20)
,('Jeans',  2,  40)
,('Jeans',  3,  60)
,('Jeans',  4,  5)
,('Skirt',  1,  10)
,('Skirt',  2,  5)
,('Skirt',  3,  30)
,('Blouse', 1,  15)
,('Blouse', 2,  40)
,('Blouse', 3,  60)
,('Blouse', 4,  15)


    select  product, [1] as quarter1,[2] as quarter2,[3] as quarter3,[4] as quarter4
from
(
select product,quarter,[amount sold] from @tmp)p
pivot
(
sum([amount sold])
for quarter in([1],[2],[3],[4])
) as pvt

输出：

product quarter1    quarter2    quarter3    quarter4
Blouse  15          40          60          15
Jeans   20          40          60          5
Skirt   10          5           30          NULL

SQL: 如何处理NULL和PARTITION BY？

SQL: How to deal with NULL and PARTITION BY?

sql

oracle

window-functions