Question

我无法理解如何使用T-SQL查询解决此问题。我有一个价格列和一个卷列。在另一张表中，a有不同音量水平的折扣。所以我的折扣表的值可以是

(StartLevel, DiscountFactor)
(0, 1);
(25, 0.95);
(50, 0.90);
(100, 0.75)

我想要的是计算总价。如果音量为35，我希望它乘以

Price x ((35-25) x 0.95 + (25-0) x 1)

如果音量为200，则应为

Price x ((200-100) x 0.75 + (100-50) x .9+(50-25) x .95+(25) x 1)

任何人都可以帮我解决这个问题吗？

Answer 1

这可以提供帮助：

DECLARE @products TABLE
    (
      id INT ,
      price MONEY ,
      volume INT
    )
DECLARE @discounts TABLE
    (
      id INT ,
      Level INT ,
      Factor MONEY
    )

INSERT  INTO @products
VALUES  ( 1, 10, 35 ),
        ( 2, 15, 200 )

INSERT  INTO @discounts
VALUES  ( 1, 0, 1 ),
        ( 2, 25, 0.95 ),
        ( 3, 50, 0.90 ),
        ( 4, 100, 0.75 )



SELECT  p.id, p.price * SUM(ca.m)
FROM    @products p
        CROSS APPLY ( SELECT    * ,
                                Factor * ( -Level + LEAD(Level) OVER ( PARTITION BY p.id ORDER BY Level, d ) ) AS m
                      FROM      ( SELECT    1 AS d ,
                                            Level ,
                                            Factor
                                  FROM      @discounts
                                  WHERE     Level < p.volume
                                  UNION ALL
                                  SELECT    2 AS d ,
                                            p.volume ,
                                            0
                                ) t
                    ) ca
GROUP BY p.id

如果没有分组，则返回：

id  price   volume  d   Level   Factor  m
1   10.00   35      1   0       1.00    25.00
1   10.00   35      1   25      0.95    9.50
1   10.00   35      2   35      0.00    NULL
2   15.00   200     1   0       1.00    25.00
2   15.00   200     1   25      0.95    23.75
2   15.00   200     1   50      0.90    45.00
2   15.00   200     1   100     0.75    75.00
2   15.00   200     2   200     0.00    NULL

然后只有group by产品和sum的{{1}}会产生：

Answer 2

对于给定的Volume和Price，您可以使用SQL Server 2012及更早版本中提供的LEAD根据间隔获得折扣。

示例数据

DECLARE @PriceTable TABLE(Volume INT,Price DECIMAL(9,2) )

DECLARE @Discount TABLE(StartLevel int, DiscountFactor DECIMAL(9,2))


INSERT INTO @PriceTable
VALUES(75, 20.5),
(150, 20),
(250, 20.5),
(0, 15);


INSERT INTO @Discount
VALUES(0, 1),
(25, 0.95),
(50, 0.90),
(100, 0.75);

<强>查询

SELECT Volume,Price,FinalPrice
FROM @PriceTable P
CROSS APPLY(
SELECT SUM(CASE WHEN (MaxLevel >=StartLevel) THEN (MaxLevel-StartLevel) ELSE 0 END *DiscountFactor)*P.Price as FinalPrice
FROM 
(
SELECT CASE WHEN LEAD(StartLevel)OVER(ORDER BY StartLevel) < P.Volume THEN LEAD(StartLevel)OVER(ORDER BY StartLevel) ELSE P.Volume END MaxLevel,StartLevel, DiscountFactor
FROM @Discount
) IQ
)T

<强>输出

Volume  Price   FinalPrice
75  20.50   1460.6250
150 20.00   2625.0000
250 20.50   4228.1250
0   15.00   0.0000

SQL查询来计算间隔折扣

2 个答案: