Question

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Running total by grouped records in table

I am trying to put together an SQL statement that returns the SUM of a value by month, but on a year to date basis. In other words, for the month of March, I am looking to get the sum of a value for the months of January, February, and March.

I can easily do a group by to get a total for each month by itself, and potentially calculate the year to date value I need in my application from this data by looping through the results set. However, I was hoping to have some of this work handled with my SQL statement.

Has anyone ever tackled this type of problem with an SQL statement, and if so, what is the trick that I am missing?

My current sql statement for monthly data is similar to the following:

Select month, year, sum(value) from mytable group by month, year

If I include a where clause on the month, and only group by the year, I can get the result for a single month that I am looking for:

select year, sum(value) from mytable where month <= selectedMonth group by year

However, this requires me to have a particular month pre-selected or to utilize 12 different SQL statements to generate one clean result set.

Any guidance that can be provided would be greatly appreciated!

Update: The data is stored on an IBM iSeries.

Answer 1

declare @Q as table 
(
mmonth INT,
value int 
)

insert into @Q
values
(1,10),
(1,12),
(2,45),
(3,23)

select sum(January) as UpToJanuary, 
sum(February)as UpToFebruary,
sum(March) as UpToMarch from (
select 
case when mmonth<=1 then sum(value) end as [January] ,
case when mmonth<=2 then sum(value) end as [February],
case when mmonth<=3 then sum(value) end as [March]
from @Q
group by mmonth
) t

Produces:

UpToJanuary UpToFebruary    UpToMarch
22          67              90

You get the idea, right?

NOTE: This could be done easier with PIVOT tables but I don’t know if you are using SQL Server or not.