Prueba:
DECLARE @t TABLE
(
ID INT ,
wac DECIMAL(30, 10) ,
item CHAR(1)
)
DECLARE @b TABLE
(
item CHAR(1) ,
baseline DECIMAL(30, 10)
)
INSERT INTO @t
VALUES ( 1, 2.31, 'A' ),
( 2, 1.10, 'A' ),
( 3, 2.13, 'A' ),
( 4, 1.34, 'A' )
INSERT INTO @b
VALUES ( 'A', 10 );
WITH ordercte
AS ( SELECT * ,
ROW_NUMBER() OVER ( PARTITION BY item ORDER BY ID ) AS rn
FROM @t
),
rec
AS ( SELECT t.item ,
t.ID ,
t.wac ,
t.rn ,
b.baseline * ( 1 + ( t.wac / 100 ) ) AS m
FROM ordercte t
JOIN @b b ON b.item = t.item
WHERE t.rn = 1
UNION ALL
SELECT t.item ,
t.ID ,
t.wac ,
t.rn ,
c.m * ( 1 + ( t.wac / 100 ) )
FROM ordercte t
JOIN rec c ON t.item = c.item
AND t.rn = c.rn + 1
)
SELECT id ,
wac ,
item ,
m
FROM rec
Salida:
id wac item m
1 2.3100000000 A 10.231000
2 1.1000000000 A 10.343541
3 2.1300000000 A 10.563858
4 1.3400000000 A 10.705414
EDITAR1
Estaba tratando de implementar el truco LOG EXP pero no pude hacerlo a menos que @usr me guiara a la solución. Así que todos los créditos para el usuario @usr:
WITH ordercte
AS ( SELECT t.ID ,
t.wac ,
t.item ,
b.baseline ,
ROW_NUMBER() OVER ( PARTITION BY t.item ORDER BY ID ) AS rn
FROM @t t
JOIN @b b ON b.item = t.item
)
SELECT baseline
* EXP(SUM(LOG(( 1 + ( wac / 100 ) ))) OVER ( PARTITION BY item ORDER BY rn )) AS m
FROM ordercte
O simplemente:
SELECT t.ID, t.wac, t.item, baseline
* EXP(SUM(LOG(( 1 + ( wac / 100 ) ))) OVER ( PARTITION BY t.item ORDER BY t.ID )) AS m
FROM @t t
JOIN @b b ON b.item = t.item
si ID es el campo por el que ordena.
Salida:
ID wac item m
1 2.3100000000 A 10.231
2 1.1000000000 A 10.343541
3 2.1300000000 A 10.5638584233
4 1.3400000000 A 10.7054141261722
EDITAR2
Para el uso de SQL 2008:
WITH cte
AS ( SELECT t.ID ,
t.wac ,
t.item ,
baseline ,
( SELECT SUM(LOG(( 1 + ( wac / 100 ) )))
FROM @t it
WHERE it.item = t.item AND it.ID <= t.ID
) AS e
FROM @t t
JOIN @b b ON b.item = t.item
)
SELECT ID, wac, item, baseline * EXP(e) AS m
FROM cte
EDITAR3
Aquí está la solución completa para SQL Server 2008 con marcación con NULL y valores negativos:
WITH cte
AS ( SELECT t.ID ,
t.wac ,
t.item ,
b.baseline ,
ca.e,
ca.n,
ca.m
FROM @t t
JOIN @b b ON b.item = t.item
CROSS APPLY(SELECT SUM(LOG(ABS(NULLIF( 1 + wac / 100 , 0)))) as e,
SUM(SIGN(CASE WHEN 1 + wac / 100 < 0 THEN 1 ELSE 0 END)) AS n,
MIN(ABS(1 + wac / 100)) AS m
FROM @t it
WHERE it.item = t.item AND it.ID <= t.ID
) ca
)
SELECT ID, wac, item, baseline *
CASE
WHEN m = 0 THEN 0
WHEN n % 2 = 1 THEN -1 * EXP(e)
ELSE EXP(e)
END as Result
FROM cte
