从小到大扣除金额，直到金额用完

Question

我有一个 SQL table 看起来像这样

CREATE TABLE #Temp_Supply 
(
    Supplier_Name Varchar(30), 
    Invoice_Number Varchar(20), 
    Amount Money
)

INSERT INTO #Temp_Supply (Supplier_Name, Invoice_Number, Amount)
    SELECT 'Supply1', 'Inv1', 1000 UNION
    SELECT 'Supply1', 'Inv2', 2000 UNION
    SELECT 'Supply1', 'Inv3', 3000 UNION
    SELECT 'Supply2', 'Inv1', 1500 UNION
SELECT 'Supply2', 'Inv2', 2500
    
CREATE TABLE #Temp_Supply_Deduction
(
    Supplier_Name Varchar(30), 
    Deduction_Amount Money
)

INSERT INTO #Temp_Supply_Deduction(Supplier_Name, Deduction_Amount)
    SELECT 'Supply1', 2500 UNION
SELECT 'Supply2', 500
    
SELECT * FROM #Temp_Supply
SELECT * FROM #Temp_Supply_Deduction

在选择供应时table从最小的发票编号开始扣除保留金额，直到金额用完

例外的输出应该是

Supplier_Name	Invoice_Number	Amount
Supply1	Inv1	0.00
Supply1	Inv2	500
Supply1	Inv3	3000
Supply2	Inv1	500.00
Supply2	Inv2	2500.00

谢谢

Answer 1

使用window函数sum() over (partition by ... order by ...)得到Amount的累加和。使用 CASE 表达式根据累计金额有条件地检查 Deduction_Amount 以确定余额金额

select d.Supplier_Name, 
       d.Deduction_Amount, 
       s.Invoice_Number, 
       Invoice_Amount = s.Amount,
       Balance = case when  d.Deduction_Amount
                      >=    sum(s.Amount) over (partition by d.Supplier_Name 
                                                order by s.Amount, 
                                                         s.Invoice_Number)
                      then  0
                      when  d.Deduction_Amount 
                      >=    sum(s.Amount) over (partition by d.Supplier_Name 
                                                    order by s.Amount, 
                                                             s.Invoice_Number)
                      -     s.Amount
                      then  sum(s.Amount) over (partition by d.Supplier_Name 
                                                    order by s.Amount, 
                                                             s.Invoice_Number)
                      -     d.Deduction_Amount
                      else  s.Amount
                      end
from   #Temp_Supply_Deduction d
       inner join #Temp_Supply s on d.Supplier_Name = s.Supplier_Name

db<>fiddle demo

顺便说一句，你在问题中的预期输出是错误的

应该是

Supplier_Name	Deduction_Amount	Invoice_Number	Invoice_Amount	Balance
Supply1	2500.0000	Inv1	1000.0000	0.0000
Supply1	2500.0000	Inv2	2000.0000	500.0000
Supply1	2500.0000	Inv3	3000.0000	3000.0000
Supply2	500.0000	Inv1	1500.0000	1000.0000
Supply2	500.0000	Inv2	2500.0000	2500.0000

从小到大扣除金额，直到金额用完

To deduct amount starting with the smallest until amount is exhausted

sql

sql-server