问题描述
我有一张巨大的桌子,上面有几个月的产品订单历史记录。我想将表格展平,以将列作为日期字段并订购总金额。见下表:
理想的输出是:
我已经尝试过 case 语句
Case when ReportMonth = '2021-07-01' then sum(total) end as '2021-07-01',Case when ReportMonth = '2021-06-01' then sum(total) end as '2021-06-01',Case when ReportMonth = '2021-05-01' then sum(total) end as '2021-05-01',Case when ReportMonth = '2020-05-01' then sum(total) end as '2020-05-01',
但后来我得到了空值和更多记录。
解决方法
考虑通过在 CASE
中运行 SUM
语句来反转嵌套表达式:
SELECT
Parent_Org
--,...other group columns,Category,SUM(CASE WHEN ReportMonth = '2021-07-01' THEN total END) AS '2021-07-01',SUM(CASE WHEN ReportMonth = '2021-06-01' THEN total END) AS '2021-06-01',SUM(CASE WHEN ReportMonth = '2021-05-01' then total END) AS '2021-05-01',SUM(CASE WHEN ReportMonth = '2020-05-01' THEN total END) AS '2020-05-01'
FROM myTable
GROUP BY
Parent_Org
--,Category