cumulative formula

how i can calculate cumulative formula in sql

i dont know formula,

any idea?

hi ssrsrnew. in reporting services you have functions that do that for you.

in t-sql you can either do:

select t1.*, (select sum(amount) from table t2 where t2.modelnum=t1.modelnum and t2.month<=t1.month) [cumulative amount]
 from table t1
 order by t1.name

select a.manufaturer,a.modelnum,a.month,sum(b.amount) as cumulative_sum 
  from table a
          left join table b on a.modelnum=b.modelnum
where a.month>=b.month
 group by a.manufaturer,a.modelnum,a.month