"select distinct" from itab data?

Question

Hi anyone know how to do a "select distinct" from itab data and do some calculation.
For example:
This is my itab result data:
Col1 | Col2    | Col3 | col4
123  |000010 |a      |  10.00
123  |000010 |b      |  2.00
123  |000010 |c      |  3.00
123  |000020 |a      |  10.50
123  |000020 |b      |  2.50
123  |000020 |c      |  3.50
123  |000030 |a      |  50.00
123  |000030 |b      |  6.00
123  |000030 |c      |  7.00
I need to do some calculation of a value a - (b value + c value) = x value and x value update back to value a col where the value of a, b, c must be match of col2.
ideally return 000010: x value =  5.00
                    000020: x value = 4.50
                    000030: x value = 37.00
How can I able to differential the data from cols2?
aish.

Answer 1

hi,
u can do this:
loop at itab.
  loop at itab into wa_itab where col2 = itab-col2.   " process all 10's, 20's
    ....do ur codition chk n calculations  here          " populate the data into new itab
  endloop.
  delete itab where col2 = itab-col2.                      " after processing delete them.
endloop.
do the calculations and populate into new internal table in the loop itself.