Question

我正在编写一个查询，它是SQL Server中存储过程的一部分。我需要在SQL Server中找到累积求和。

变量将保存一个整数值，例如100。我们说

Declare @Variable int = 100

现在@NewVariable将具有以下公式：

@NewVariable = @Variable * (1 - 0.005)

因此@NewVariable = 99.5

现在，@NewestVariable将具有以下公式;

@NewestVariable = @NewVariable * (1 - 0.005)

因此@NewestVariable的值为99.00

同样，这种计算将发生24次，所有结果将在结束时总和。

因此最终结果将是：100 + 99.5 +99.00 + .... ...

我尝试使用@Count Variable（DECLARE @COUNT INT = 24）并使用While循环来实现所需的结果，但我不确定我是否正确？

请求帮助！

谢谢！

Answer 1

您可以使用CTE执行以下操作：

declare @variable int = 100
;with cte as
(
 select convert(numeric(8,2), @variable) as var, 1 as recCount
 union all
 select convert(numeric(8,2), @variable * (1 - recCount*0.005)) as var, recCount+1 as recCount 
 from cte
 where recCount < 24
)
select sum(var) as total from cte

Working Fiddle Demo

修改：根据@ peter.petrov的评论进行调整以解决舍入错误

如果您需要在计算前获取每行的值，请使用 this fiddle

Answer 2

试试这段代码。

declare @Variable decimal(20,10);
set @Variable = 100;

declare @Sum decimal(20,10);
set @Sum = 0;

declare @cnt int;
set @cnt = 1;

while (@cnt <= 24) 
begin
    set @Sum = @Sum + @Variable;
    set @Variable = @Variable * (1.0 - 0.005);
    set @cnt = @cnt + 1;
end;

select @Sum;

Answer 3

一个简单的答案就是这样

DECLARE @Variable INT = 100
SELECT @Variable
DECLARE @counter INT = 1
DECLARE @SumVariable NUMERIC(20,2) = @Variable
DECLARE @NewVariable NUMERIC(20,2) = @Variable

WHILE(@counter<24)
BEGIN
    SET @NewVariable = @NewVariable * 0.995
    SET @SumVariable = @SumVariable + @NewVariable
    SET @counter = @counter+1
END
SELECT @SumVariable

Answer 4

您还可以使用"quirky update"来避免while循环。如果您没有在中间结果中进行交互，只需修改最后一个代码行以仅选择max(total)。

DECLARE @total DECIMAL(10,3) = 0.000

;WITH "data" AS
(
    SELECT CAST( 100 AS DECIMAL(10,3)) AS id
    UNION ALL
    SELECT CAST( id * ( 1 - 0.005 ) AS DECIMAL(10,3)) FROM "data" WHERE id > 100 * (1 - 21 * 0.005)
)
SELECT 
    id, total = CAST( 0.000 AS DECIMAL(10,3))
INTO #temp
FROM 
    "data" 
OPTION ( MAXRECURSION 23 );

UPDATE t SET @total = total = @total + id FROM #temp t

SELECT * FROM #temp

请参阅SQL-Fiddle进行测试。

SQL Server中的累积求和

4 个答案: