帶有查詢和分組依據的 SQL Sum

Question

我有2張桌子：

像這樣，並希望通過 ProductCode = Discount-1000 上的條件來計算 tblsoinvoiceheader 上的賬單和子查詢的總和

我應該有什么樣的查詢？

Answer 1

要在tblsoinvoiceheader准備數據，我們需要使用這樣的查詢：

select TransactionDate, 
       count(*) CountOfBill, 
       sum(InvoiceAmountWithTax) InvoiceAmountWithTax 
from tblsoinvoiceheader
group by TransactionDate

然后將其與以下查詢的結果連接：

select (-1)*LineAmountWithTax
from tblsoinvoiceitem
where ProductCode = 'Discount-1000'

加起來：

select * from (
    select (-1)*LineAmountWithTax
    from tblsoinvoiceitem
    where ProductCode = 'Discount-1000'
-- i used cross join because you didn't specify joining condition and it looks like you want to 
-- join all recrods
) a cross join (
    select TransactionDate, 
           count(*) CountOfBill, 
           sum(InvoiceAmountWithTax) InvoiceAmountWithTax 
    from tblsoinvoiceheader
    group by TransactionDate
) b

Answer 2

如果每張發票最多有一個DISCOUNT行，則可以使用：

SELECT h.TransactionDate,
       COUNT(*) AS CountOfBill,
       SUM(h.InvoiceAmountWithTax) AS InvoiceAmountWithTax,
       SUM(CASE WHEN i.Remark = 'Discount' THEN -i.LineAmountWithTax END) AS Discount
FROM tblsoinvoiceheader h LEFT JOIN
     tblsoinvoiceitem i
     ON i.DocNo = h.DocNo AND
        i.Remark = 'Discount'
GROUP BY h.TransactionDate;

如果每個文檔可以有多個折扣，則需要預先匯總。