SUM two fileds from different rows from the same table

Question

I would like to SUM two fileds from different rows from the same table but I don't know how to do that.
E.g.
BillingTransactionsIndex      CreateDate      UserType      UserIndex      TransType      Reference      Total      Balance
2      6/5/2008 15:02      1      51      1      150      -288.2      -288.2
5      6/8/2008 11:55      1      51      1      157      -1.58674      -289.787
In the table above I want SUM fields Total and Balance for the first row and the the next row SUM 2nd row Total with 1st row Balance
Please help
Thanks

Answer 1

SQL> with tbl as
  2  (select 1 as ID,  90 as total from dual
  3          union all
  4  select 2 as ID,  23 as total  from dual
  5          union all
  6  select 3 as ID,  15 as total  from dual
  7          union all
  8  select 4 as ID,  20 as total  from dual)
  9  select id , total, sum(total) over (order by ID) as balance from tbl
10  /
        ID      TOTAL    BALANCE
         1         90         90
         2         23        113
         3         15        128
         4         20        148
SQL>