TSQL cumulative column from previous row [duplicate] - tsql

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Possible Duplicate:
Calculate a Running Total in SqlServer
I need to use values from previous row inorder to generate a cumulative value as shown below. Always for each Code for the year 2000 the starting Base is 100.
I need to ahieve this using tsql code.
id Code Yr Rate Base
1 4 2000 5 100
2 4 2001 7 107 (100+7)
3 4 2002 4 111 (107+4)
4 4 2003 8 119 (111+8)
5 4 2004 10 129 (119+10)
6 5 2000 2 100
7 5 2001 3 103 (100+3)
8 5 2002 8 111 (103+8)
9 5 2003 5 116 (111+5)
10 5 2004 4 120 (116+4)

Answer 1

OK. We have table like this
CREATE Table MyTbl(id INT PRIMARY KEY IDENTITY(1,1), Code INT, Yr INT, Rate INT)
And we would like to calculate cumulative value by Code.
So we can use query like this:
1) recursion (requires more resources, but outputs the result as in the example)
with cte as
(SELECT *, ROW_NUMBER()OVER(PARTITION BY Code ORDER BY Yr ASC) rn
FROM MyTbl),
recursion as
(SELECT id,Code,Yr,Rate,rn, CAST(NULL as int) as Tmp_base, CAST('100' as varchar(25)) AS Base FROM cte
WHERE rn=1
UNION ALL
SELECT cte.id,cte.Code,cte.Yr,cte.Rate,cte.rn,
CAST(recursion.Base as int),
CAST(recursion.Base+cte.Rate as varchar(25))
FROM recursion JOIN cte ON recursion.Code=cte.Code AND recursion.rn+1=cte.rn
)
SELECT id,Code,Yr,Rate,
CAST(Base as varchar(10))+ISNULL(' ('+ CAST(Tmp_base as varchar(10))+'+'+CAST(Rate as varchar(10))+')','') AS Base
FROM recursion
ORDER BY 1
OPTION(MAXRECURSION 0)
2) or we can use a faster query without using recursion. but the result is impossible to generate the strings like '107 (100+7)' (only strings like '107')
SELECT *,
100 +
(SELECT ISNULL(SUM(rate),0) /*we need to calculate only the sum in subquery*/
FROM MyTbl AS a
WHERE
a.Code=b.Code /*the year in subquery equals the year in main query*/
AND a.Yr<b.Yr /*main feature in our subquery*/
) AS base
FROM MyTbl AS b