SQL查询：包含两个基于来自同一表的不同条件的求和

Question

我目前有以下sql查询

SELECT [Date], DATENAME(dw,[Date]) AS Day, SUM(Units) AS TotalUnits
FROM tblTimesheetEntries 
WHERE UserID = 'PJW' 
AND Date >= '2013-01-01' 
GROUP BY [Date] 
ORDER BY [Date] DESC;

它返回给定用户和日期的总计[单位]。

但是，我想根据新的标准（即[Units]是否在“可充电”位置）来生成两个单独的总计单位。tblTimeSheets中有一个称为Chargeable的字段，它是一个布尔值（true表示chargeable，false表示false）。如何将其合并为每种类型的单位显示两个总和？

Answer 1

您可以将CASE与一起使用SUM()来计算单独的总计：

SELECT [Date], 
    DATENAME(dw,[Date]) AS Day, 
    sum(case when Chargeable = 1 then Units else 0 end) ChargeableTotal,
    sum(case when Chargeable = 0 then Units else 0 end) NotChargeableTotal,
    sum(Units) AS TotalUnits
FROM tblTimesheetEntries 
WHERE UserID = 'PJW' 
    AND Date >= '2013-01-01' 
GROUP BY [Date] 
ORDER BY [Date] DESC;