如何在SQL中使用嵌套的Group by

Question

我有3个表：发票，服务发票和服务（参阅附图）

我想创建一份摘要报告，显示每项服务的每日销售额（现金总额，借记总额），我试试这个：

SELECT Service.ServiceName, SUM(ServicesinInvoice.Total) AS Total, COUNT(*) AS Count, Service.ServiceID
FROM ServicesinInvoice INNER JOIN
     Service ON ServicesinInvoice.ServiceId = Service.ServiceID INNER JOIN
     Invoice ON ServicesinInvoice.InvoiceId = Invoice.InvoiceID
WHERE (dbo.Invoice.InvoiceDate >= CONVERT(DATETIME, '2016-06-11 00:00:00', 102)) 
GROUP BY dbo.Service.ServiceName, dbo.Service.ServiceID

关于sql代码给出了每项服务的总数，我想要的是获得每项服务的现金总额和借方总额（按服务分组）。

在表格（发票）中，我有 ClientId 列，如果 ClientId = 1 ，则表示现金，否则为借方。

请帮助完成

提前致谢。

Answer 1

如果我理解正确，可以通过条件聚合完成：

SELECT Service.ServiceID,Service.ServiceName, 
       SUM(CASE WHEN Invoice.ClientId = 1 THEN ServicesinInvoice.Total ELSE 0 END) AS Total_cash,
       SUM(CASE WHEN Invoice.ClientId <> 1 THEN ServicesinInvoice.Total ELSE 0 END) AS Total_debit,
       COUNT(*) AS Count 
FROM ServicesinInvoice INNER JOIN
     Service ON ServicesinInvoice.ServiceId = Service.ServiceID INNER JOIN
     Invoice ON ServicesinInvoice.InvoiceId = Invoice.InvoiceID
WHERE (dbo.Invoice.InvoiceDate >= CONVERT(DATETIME, '2016-06-11 00:00:00', 102)) 
GROUP BY dbo.Service.ServiceName, dbo.Service.ServiceID