SQL按年汇总报告，寻找一种优雅的解决方案 [英] SQL sum by year report, looking for an elegant solution

问题描述

我有一个包含3列的表格:ItemCode，Quantity和DocDate. 我想以更优雅"的方式创建以下报告:

I have a table with 3 columns: ItemCode, Quantity and DocDate. I would like to create the following report in a more "elegant" way:

SELECT T0.ItemCode, 
       (SELECT SUM(QUANTITY) FROM MyTable T1 WHERE YEAR(T0.DocDate) = 2011 AND T0.ItemCode = T1.ItemCode) AS '2011',
       (SELECT SUM(QUANTITY) FROM MyTable T1 WHERE YEAR(T0.DocDate) = 2012 AND T0.ItemCode = T1.ItemCode) AS '2012'
FROM MyTable T0
GROUP BY T0.ItemCode, YEAR(T0.DocDate)

我敢肯定，有一种更好，更有效的方式编写此代码，但是我无法提出正确的语法.有什么想法吗?

I'm pretty sure there's a better, more efficient way to write this but I can't come up with the right syntax. Any ideas?

推荐答案

您可以尝试以下操作:

SELECT  T0.ItemCode, 
        SUM(CASE WHEN YEAR(T0.DocDate) = 2011 THEN QUANTITY ELSE 0 END) AS '2011',
        SUM(CASE WHEN YEAR(T0.DocDate) = 2012 THEN QUANTITY ELSE 0 END) AS '2012'
FROM    MyTable T0
GROUP BY 
        T0.ItemCode

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