Aquí hay un enfoque alternativo que requiere LAG() que está disponible en SQL 2012, pero tenga en cuenta que los datos de muestra no contienen "28 días distintos" antes de cada fecha. Además, no se conoce el tipo de datos real que se utiliza (fecha/pequeña fechahora/fechahora/fechahora2) ni se sabe si es necesario truncar la hora de la fecha. Entonces, con algunas advertencias, este enfoque crea una serie de rangos de fechas para las 28 fechas distintas (pero si los datos no las proporcionan, entonces son 28 días transcurridos). Aquí hay una demostración de sqlfiddle
Configuración del esquema de PostgreSQL 9.3 :(ya que SQL Server no opera en sqlfiddle)
CREATE TABLE Table1
(theDate timestamp, Value int, promo int, item int)
;
INSERT INTO Table1
(theDate, Value, promo, item)
VALUES
('2011-01-01 00:00:00', 626, 0, 1230),
('2011-01-02 00:00:00', 231, 1, 1230),
('2011-01-03 00:00:00', 572, 1, 1230),
('2011-01-04 00:00:00', 775, 1, 1230),
('2011-01-05 00:00:00', 660, 1, 1230),
('2011-01-06 00:00:00', 662, 1, 1230),
('2011-01-07 00:00:00', 541, 1, 1230),
('2011-01-08 00:00:00', 849, 1, 1230),
('2011-01-09 00:00:00', 632, 1, 1230),
('2011-01-10 00:00:00', 906, 1, 1230),
('2011-01-11 00:00:00', 961, 1, 1230),
('2011-01-12 00:00:00', 361, 0, 1230),
('2012-01-01 00:00:00', 461, 0, 1230),
('2012-01-02 00:00:00', 928, 1, 1230),
('2012-01-03 00:00:00', 855, 0, 1230),
('2012-01-04 00:00:00', 605, 0, 1230),
('2012-01-05 00:00:00', 83, 0, 1230),
('2012-01-06 00:00:00', 44, 0, 1230),
('2012-01-07 00:00:00', 382, 0, 1230),
('2012-01-08 00:00:00', 862, 0, 1230),
('2012-01-09 00:00:00', 549, 0, 1230),
('2012-01-10 00:00:00', 632, 0, 1230),
('2012-01-11 00:00:00', 2, 0, 1230),
('2012-01-12 00:00:00', 26, 0, 1230)
;
Consulta 1 :
select
t1.item
, ranges.theStart
, ranges.theEnd
, sum(t1.value)
, sum(t1.value) / 28 avg
from (
select
coalesce(lag(theDay,28) over(order by theDay) , theDay - INTERVAL '28 DAYS') as theStart
, theDay as theEnd
from (
select distinct cast(thedate as date) theDay from Table1
) days
) ranges
inner join table1 t1 on theDate between ranges.theStart and ranges.theEnd
group by
t1.item
, ranges.theStart
, ranges.theEnd
| item | thestart | theend | sum | avg |
|------|----------------------------|---------------------------|------|-----|
| 1230 | December, 04 2010 00:00:00 | January, 01 2011 00:00:00 | 626 | 22 |
| 1230 | December, 05 2010 00:00:00 | January, 02 2011 00:00:00 | 857 | 30 |
| 1230 | December, 06 2010 00:00:00 | January, 03 2011 00:00:00 | 1429 | 51 |
| 1230 | December, 07 2010 00:00:00 | January, 04 2011 00:00:00 | 2204 | 78 |
| 1230 | December, 08 2010 00:00:00 | January, 05 2011 00:00:00 | 2864 | 102 |
| 1230 | December, 09 2010 00:00:00 | January, 06 2011 00:00:00 | 3526 | 125 |
| 1230 | December, 10 2010 00:00:00 | January, 07 2011 00:00:00 | 4067 | 145 |
| 1230 | December, 11 2010 00:00:00 | January, 08 2011 00:00:00 | 4916 | 175 |
| 1230 | December, 12 2010 00:00:00 | January, 09 2011 00:00:00 | 5548 | 198 |
| 1230 | December, 13 2010 00:00:00 | January, 10 2011 00:00:00 | 6454 | 230 |
| 1230 | December, 14 2010 00:00:00 | January, 11 2011 00:00:00 | 7415 | 264 |
| 1230 | December, 15 2010 00:00:00 | January, 12 2011 00:00:00 | 7776 | 277 |
| 1230 | December, 04 2011 00:00:00 | January, 01 2012 00:00:00 | 461 | 16 |
| 1230 | December, 05 2011 00:00:00 | January, 02 2012 00:00:00 | 1389 | 49 |
| 1230 | December, 06 2011 00:00:00 | January, 03 2012 00:00:00 | 2244 | 80 |
| 1230 | December, 07 2011 00:00:00 | January, 04 2012 00:00:00 | 2849 | 101 |
| 1230 | December, 08 2011 00:00:00 | January, 05 2012 00:00:00 | 2932 | 104 |
| 1230 | December, 09 2011 00:00:00 | January, 06 2012 00:00:00 | 2976 | 106 |
| 1230 | December, 10 2011 00:00:00 | January, 07 2012 00:00:00 | 3358 | 119 |
| 1230 | December, 11 2011 00:00:00 | January, 08 2012 00:00:00 | 4220 | 150 |
| 1230 | December, 12 2011 00:00:00 | January, 09 2012 00:00:00 | 4769 | 170 |
| 1230 | December, 13 2011 00:00:00 | January, 10 2012 00:00:00 | 5401 | 192 |
| 1230 | December, 14 2011 00:00:00 | January, 11 2012 00:00:00 | 5403 | 192 |
| 1230 | December, 15 2011 00:00:00 | January, 12 2012 00:00:00 | 5429 | 193 |
Nota:para SQL Server
- en lugar de
theDay - INTERVAL '28 DAYS'use dateadd(day,-28,theDay)
