DB2，按年份分组和求和，其中年份是列值

Question

我目前有一个像这样的 db2 查询：

SELECT
         NUMBER ,
         YEAR(newDate),
         dollarAMT - CAST ( coupon * dollarAMT AS DECIMAL ( 12 , 2 ) ) AS TOTAL
        FROM ORDERING A
        LEFT JOIN table.clients CL ON CL . clientNUmber = A . clientNumber 
        WHERE
        newDate >= '2019-01-01'
         order by newDate asc;

这给出了这样的值：

123   2019   100.00
123   2019   200.00
123   2020   500.00
123   2020   800.00  
123   2021   1000.00

虽然我正在尝试获得此结果：

Number   2019    2020      2021
123     300.00   1300.00  1000.00

我如何在 DB2 中更改此设置，以便年份成为列名并按年份对销售额进行分组？

Answer 1

您需要旋转数据，但 DB2 不支持 PIVOT ，因此您可以这样做：

select
    number,
    sum(case when YEAR(newDate) = 2019 then (dollarAMT - CAST ( coupon * dollarAMT AS DECIMAL ( 12 , 2 ) ) ) end) as 2019,
    sum(case when YEAR(newDate) = 2020 then (dollarAMT - CAST ( coupon * dollarAMT AS DECIMAL ( 12 , 2 ) ) ) end) as 2020,
    sum(case when YEAR(newDate) = 2021 then (dollarAMT - CAST ( coupon * dollarAMT AS DECIMAL ( 12 , 2 ) ) ) end) as 2021,
FROM ORDERING A
LEFT JOIN table.clients CL ON CL.clientNUmber = A.clientNumber
WHERE newDate >= '2019-01-01'
group by number 
order by number asc;

但如果您可以按行而不是按列显示它们，查询就会简单得多，并且不需要为即将到来的每一年修改它：

SELECT
    NUMBER,
    YEAR(newDate),
    sum(dollarAMT - CAST (coupon * dollarAMT AS DECIMAL (12, 2))) AS TOTAL
FROM  ORDERING A
LEFT JOIN table.clients CL ON CL.clientNUmber = A.clientNumber
WHERE newDate >= '2019-01-01'
group by NUMBER, YEAR(newDate)
order by  NUMBER, YEAR(newDate) asc;

DB2，按年份分组和求和，其中年份是列值

DB2, group and sum by year where the year is a column value

sql

db2