help!!! calculate average rolling 4 last weeks
-
Hi All,
I need your help.
Database: SQL SERVER 2008R2
I want to calculte for a year and a week the average of value of the 4 last weeks.
I have data a table like that:
YEAR WEEKS VALUE
2012 1 3000
2012 2 5000
2012 3 6000
2012 4 7000
2012 5 8000
2012 6 9000
2012 7 1000
2012 8 6000
And I want that :
YEAR WEEKS VALUE
2012 1 ( Average value for week 49, 50, 51, 52 for the year 2011)
2012 2 ( Average value for week 50, 51, 52 for the year 2011 and week 1 for the year 2012)
2012 3 ( Average value for week 51, 52 for the year 2011 and week 1, 2 for the year 2012)
2012 4 ( Average value for week 52 for the year 2011 and week 1, 2, 3 for the year 2012)
2012 5 5250 -> ( Average value for week 1, 2, 3 , 4 for the year 2012)
2012 6 6500 -> ( Average value for week 2, 3 , 4, 5 for the year 2012)
Thank U for your help
-
Here you go..
-- Creating tableCREATE TABLE year_week_value
(
year INT,
week INT,
value INT
);
-- Inserting test values
INSERT year_week_value
VALUES
(2011,49,3000),
(2011,50,5000),
(2011,51,6000),
(2011,52,7000),
(2012,1,3000),
(2012,2,5000),
(2012,3,6000),
(2012,4,7000),
(2012,5,8000),
(2012,6,9000),
(2012,7,1000),
(2012,8,6000);
-- Resultant query
SELECT a.year,
a.week,
.25 * ( Isnull(b.value, 0) + Isnull(c.value, 0)
+ Isnull(d.value, 0) + Isnull(e.value, 0) ) AvgVal
FROM year_week_value a
LEFT JOIN year_week_value b
ON b.year = Year(Dateadd(wk, a.week - 2, Dateadd(year, a.year - 1900, 0)))
AND b.week = Datepart(wk, Dateadd(wk, a.week - 2, 0))
LEFT JOIN year_week_value c
ON c.year = Year(Dateadd(wk, a.week - 3, Dateadd(year, a.year - 1900, 0)))
AND c.week = Datepart(wk, Dateadd(wk, a.week - 3, 0))
LEFT JOIN year_week_value d
ON d.year = Year(Dateadd(wk, a.week - 4, Dateadd(year, a.year - 1900, 0)))
AND d.week = Datepart(wk, Dateadd(wk, a.week - 4, 0))
LEFT JOIN year_week_value e
ON e.year = Year(Dateadd(wk, a.week - 5, Dateadd(year, a.year - 1900, 0)))
AND e.week = Datepart(wk, Dateadd(wk, a.week - 5, 0))
ORDER BY a.year,
a.week
~ Lokesh Vij
Guidelines for quicker answers on T-SQL question[/url]
Guidelines for answers on Performance questionsLink to my Blog Post --> www.SQLPathy.com[/url]
Follow me @Twitter
-
Here is another way using Correlated SubQuery:
Create Table Ex1
(
YEAR int,
WEEKS int,
VALUE int
)
Insert Into Ex1
Select 2012, 1,3000
Union ALL
Select 2012, 2,5000
Union ALL
Select 2012, 3,6000
Union ALL
Select 2012, 4,7000
Union ALL
Select 2012, 5,8000
Union ALL
Select 2012, 6,9000
Union ALL
Select 2012, 7,1000
Union ALL
Select 2012, 8,6000
;With CTE
As
(
Select *, ROW_NUMBER() Over(Order By Year, Weeks) As rn From Ex1
)
Select *, (Case When (Select Count(*) From CTE Where rn < a.rn) >= 4 Then (Select AVG(VALUE) From CTE As b Where b.rn IN(Select Top 4 rn From CTE Where rn < a.rn Order By rn DESC)) Else '' End) As AvgValue
From CTE As a
Order By YEAR, WEEKS
Hope it helps.:-)
-
Hi Lokesh,
Thank You for your answer.
I tested the script but the execution is too long ( about 30 minutes for 1064 lines) :(.
Do U think that it is possible to optimize the script ?
Can I replace 'left join' by ' inner join ' ??
Lidou
-
Hi Vinu,
thank U for your answer !!!
I tested the script but I have an error !!! it is in french .
Msg 116, Niveau 16, État 1, Ligne 8
Une seule expression peut être spécifiée dans la liste de sélection quand la sous-requête n'est pas introduite par EXISTS.
So I can Use only one expression in a sub request. 🙁
-
Hi Lokesh,
that works well with index .
Thank U !!!!!!!!!
-
I guess I'd do it like this: -
SELECT year, week, value, ISNULL(AvgVal,0) AS AvgValFROM (SELECT year, week, value, ROW_NUMBER() OVER(ORDER BY year,week)
FROM year_week_value) a(year,week,value,pos)
OUTER APPLY (SELECT SUM(b.value)/(COUNT(1)*1.00)
FROM (SELECT year, week, value, ROW_NUMBER() OVER(ORDER BY year,week)
FROM year_week_value) b(year,week,value,pos)
WHERE a.pos >= b.pos AND a.pos-4 <= b.pos) ab(AvgVal);
SELECT year, week, value, ISNULL(AvgVal,0) AS AvgValFROM (SELECT year, week, value, ROW_NUMBER() OVER(ORDER BY year,week)
FROM year_week_value) a(year,week,value,pos)
OUTER APPLY (SELECT SUM(b.value)/(COUNT(1)*1.00)
FROM (SELECT year, week, value, ROW_NUMBER() OVER(ORDER BY year,week)
FROM year_week_value) b(year,week,value,pos)
WHERE a.pos > b.pos AND a.pos-5 < b.pos) ab(AvgVal);
However, all three of the solutions so far give different results so we may have all misunderstood your requirements.
So, let's look at some sample data: -
-- Creating tableCREATE TABLE year_week_value (year INT, week INT, value INT);
-- Inserting test values
INSERT year_week_value
VALUES (2011, 49, 3000), (2011, 50, 5000), (2011, 51, 6000), (2011, 52, 7000),
(2012, 1, 3000), (2012, 2, 5000), (2012, 3, 6000), (2012, 4, 7000),
(2012, 5, 8000), (2012, 6, 9000), (2012, 7, 1000), (2012, 8, 6000);
Now the three solutions: -
-- Lokesh VijSELECT a.year, a.week, .25 * (Isnull(b.value, 0) + Isnull(c.value, 0) + Isnull(d.value, 0) + Isnull(e.value, 0)) AvgVal, A.value
FROM year_week_value a
LEFT JOIN year_week_value b ON b.year = Year(Dateadd(wk, a.week - 2, Dateadd(year, a.year - 1900, 0)))
AND b.week = Datepart(wk, Dateadd(wk, a.week - 2, 0))
LEFT JOIN year_week_value c ON c.year = Year(Dateadd(wk, a.week - 3, Dateadd(year, a.year - 1900, 0)))
AND c.week = Datepart(wk, Dateadd(wk, a.week - 3, 0))
LEFT JOIN year_week_value d ON d.year = Year(Dateadd(wk, a.week - 4, Dateadd(year, a.year - 1900, 0)))
AND d.week = Datepart(wk, Dateadd(wk, a.week - 4, 0))
LEFT JOIN year_week_value e ON e.year = Year(Dateadd(wk, a.week - 5, Dateadd(year, a.year - 1900, 0)))
AND e.week = Datepart(wk, Dateadd(wk, a.week - 5, 0))
ORDER BY a.year, a.week;
-- vinu512
WITH CTE
AS (SELECT *, ROW_NUMBER() OVER (ORDER BY year, week) AS rn
FROM year_week_value
)
SELECT *, (CASE WHEN (SELECT Count(*)
FROM CTE
WHERE rn < a.rn) >= 4
THEN (SELECT AVG(VALUE)
FROM CTE AS b
WHERE b.rn IN (SELECT TOP 4 rn
FROM CTE
WHERE rn < a.rn
ORDER BY rn DESC
))
ELSE ''
END) AS AvgValue
FROM CTE AS a
ORDER BY year, week;
-- Cadavre
SELECT year, week, value, ISNULL(AvgVal,0) AS AvgVal
FROM (SELECT year, week, value, ROW_NUMBER() OVER(ORDER BY year,week)
FROM year_week_value) a(year,week,value,pos)
OUTER APPLY (SELECT SUM(b.value)/(COUNT(1)*1.00)
FROM (SELECT year, week, value, ROW_NUMBER() OVER(ORDER BY year,week)
FROM year_week_value) b(year,week,value,pos)
WHERE a.pos >= b.pos AND a.pos-4 <= b.pos) ab(AvgVal);
And the results: -
---------------------------------------------------------------------------Lokesh Vij
---------------------------------------------------------------------------
year week AvgVal value
----------- ----------- --------------------------------------- -----------
2011 49 0.00 3000
2011 50 750.00 5000
2011 51 2000.00 6000
2011 52 3500.00 7000
2012 1 5250.00 3000
2012 2 5250.00 5000
2012 3 5250.00 6000
2012 4 5250.00 7000
2012 5 5250.00 8000
2012 6 6500.00 9000
2012 7 7500.00 1000
2012 8 6250.00 6000
---------------------------------------------------------------------------
---------------------------------------------------------------------------
vinu512
---------------------------------------------------------------------------
year week value rn AvgValue
----------- ----------- ----------- -------------------- -----------
2011 49 3000 1 0
2011 50 5000 2 0
2011 51 6000 3 0
2011 52 7000 4 0
2012 1 3000 5 5250
2012 2 5000 6 5250
2012 3 6000 7 5250
2012 4 7000 8 5250
2012 5 8000 9 5250
2012 6 9000 10 6500
2012 7 1000 11 7500
2012 8 6000 12 6250
---------------------------------------------------------------------------
---------------------------------------------------------------------------
Cadavre
---------------------------------------------------------------------------
year week value AvgVal
----------- ----------- ----------- ---------------------------------------
2011 49 3000 0.000000000000000
2011 50 5000 3000.000000000000000
2011 51 6000 4000.000000000000000
2011 52 7000 4666.666666666666666
2012 1 3000 5250.000000000000000
2012 2 5000 5250.000000000000000
2012 3 6000 5250.000000000000000
2012 4 7000 5250.000000000000000
2012 5 8000 5250.000000000000000
2012 6 9000 6500.000000000000000
2012 7 1000 7500.000000000000000
2012 8 6000 6250.000000000000000
So I guess my advice is to always post sample data and expected results in the future. But for this problem, you need to figure out whether any of these solutions give the results you expect.
Forever trying to learn
My blog - http://www.cadavre.co.uk/
For better, quicker answers on T-SQL questions, click on the following...http://www.sqlservercentral.com/articles/Best+Practices/61537/
For better, quicker answers on SQL Server performance related questions, click on the following...http://www.sqlservercentral.com/articles/SQLServerCentral/66909/ -
Lidou123 (12/20/2012)
Hi Vinu,thank U for your answer !!!
I tested the script but I have an error !!! it is in french .
Msg 116, Niveau 16, État 1, Ligne 8
Une seule expression peut être spécifiée dans la liste de sélection quand la sous-requête n'est pas introduite par EXISTS.
So I can Use only one expression in a sub request. 🙁
Hi Lidou,
Are you executing the same script that I posted??.....It seems to work perfectly on my box and I think on Cadavre's box as well.
-
Lidou123 (12/20/2012)
Hi Lokesh,that works well with index .
Thank U !!!!!!!!!
Gald that you found out a way to improve the query using an Index 🙂
~ Lokesh Vij
Guidelines for quicker answers on T-SQL question[/url]
Guidelines for answers on Performance questionsLink to my Blog Post --> www.SQLPathy.com[/url]
Follow me @Twitter
-
Cadavre (12/20/2012)
So I guess my advice is to always post sample data and expected results in the future. But for this problem, you need to figure out whether any of these solutions give the results you expect.I take by your words Cadavre!
OP - please take care in future. That will really help you and us both 🙂
~ Lokesh Vij
Guidelines for quicker answers on T-SQL question[/url]
Guidelines for answers on Performance questionsLink to my Blog Post --> www.SQLPathy.com[/url]
Follow me @Twitter
-
vinu512 (12/20/2012)
Are you executing the same script that I posted??.....It seems to work perfectly on my box and I think on Cadavre's box as well.I think your script is fine!
~ Lokesh Vij
Guidelines for quicker answers on T-SQL question[/url]
Guidelines for answers on Performance questionsLink to my Blog Post --> www.SQLPathy.com[/url]
Follow me @Twitter
-
Thank U guys.
just let me test the 3 scripts and I will come back !!!!!!!!
Thank U
Lidou
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Lidou123 (12/19/2012)
Hi All,YEAR WEEKS VALUE
2012 1 3000
2012 2 5000
2012 3 6000
2012 4 7000
2012 5 8000
2012 6 9000
2012 7 1000
2012 8 6000
And I want that :
YEAR WEEKS VALUE
2012 1 ( Average value for week 49, 50, 51, 52 for the year 2011)
2012 2 ( Average value for week 50, 51, 52 for the year 2011 and week 1 for the year 2012)
2012 3 ( Average value for week 51, 52 for the year 2011 and week 1, 2 for the year 2012)
2012 4 ( Average value for week 52 for the year 2011 and week 1, 2, 3 for the year 2012)
2012 5 5250 -> ( Average value for week 1, 2, 3 , 4 for the year 2012)
2012 6 6500 -> ( Average value for week 2, 3 , 4, 5 for the year 2012)
Thank U for your help
Guys. I'm not sure I'm reading the OP's problem quite the same way you are.
He seems to want the average to represent the 4 weeks prior to but not including the current week. So if there's data for weeks 48-52, the first week to show is week 1. At the same time, since there's data for up through week 8, that means the value for week 9 should show.
Something like this perhaps?
-- Creating table
CREATE TABLE #year_week_value
(
year INT,
week INT,
value INT
);
-- Inserting test values
INSERT #year_week_value (year, week, value)
VALUES
(2011,49,3000),
(2011,50,5000),
(2011,51,6000),
(2011,52,7000),
(2012,1,3000),
(2012,2,5000),
(2012,3,6000),
(2012,4,7000),
(2012,5,8000),
(2012,6,9000),
(2012,7,1000),
(2012,8,6000);
-- Dwain.C
SELECT year=MAX(yr_wk/100+CASE WHEN yr_wk%100=52 THEN 1 ELSE 0 END)
,week=MAX(CASE WHEN yr_wk%100=52 THEN 1 ELSE 1+(yr_wk%100) END)
,avgvalue=SUM((value + value2 + value3 + value4) / 4)
FROM (
SELECT yr_wk=year*100+week
,value, value2=0, value3=0, value4=0
FROM #year_week_value
UNION ALL
SELECT CASE WHEN week + 1 > 52 THEN (year+1)*100 + (week + 1)-52 ELSE year*100 + week + 1 END
, 0, value2=value, value3=0, value4=0
FROM #year_week_value
UNION ALL
SELECT CASE WHEN week + 2 > 52 THEN (year+1)*100 + (week + 2)-52 ELSE year*100 + week + 2 END
, 0, value2=0, value3=value, value4=0
FROM #year_week_value
UNION ALL
SELECT CASE WHEN week + 3 > 52 THEN (year+1)*100 + (week + 3)-52 ELSE year*100 + week + 3 END
, 0, value2=0, value3=0, value4=value
FROM #year_week_value) a
GROUP BY yr_wk
HAVING COUNT(yr_wk) = 4
DROP TABLE #year_week_value
My mantra: No loops! No CURSORs! No RBAR! Hoo-uh![/I]My thought question: Have you ever been told that your query runs too fast?
My advice:
INDEXing a poor-performing query is like putting sugar on cat food. Yeah, it probably tastes better but are you sure you want to eat it?
The path of least resistance can be a slippery slope. Take care that fixing your fixes of fixes doesn't snowball and end up costing you more than fixing the root cause would have in the first place.Need to UNPIVOT? Why not CROSS APPLY VALUES instead?[/url]
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