Hey!!! thanks thanks thanks to all of you!.
Your just wonderfull and the help you provide is priceless.
I think I will solve my problem now.
I've read about the use of variables in the manual but
It would have taken me a lot of time to figure something like this.
Thanks again and to all the rest of the people
who answered my question
Gratefully
Mauricio
On Fri, 2004-08-13 at 11:55, Keith Ivey wrote:
> Mauricio Pellegrini wrote:
>
> >and would like to obtain this result from a query
> >
> > Col1 Col2 Col3
> > 1 20 20
> > 1 10 30
> > 1 20 50
> > 2 10 10
> > 2 5 15
> > 3 10 10
> >
> >Column Col3 should carry forward and sum values from Col2
> >
> Something like this should work, using two variables, @total and @prev:
>
> SELECT Col1, Col2, @total := IF(@prev = Col1, @total + Col2, Col2 +
> (@prev := Col1) - Col1)
> FROM table_name
> ORDER BY Col1;
>
> The way I'm setting @prev every time Col1 changes is a bit klugy (having
> to add it in and
> then subtract Col1 to fix it), but it seems to work.
>
> Hmm, if you change the order of the result columns you can avoid the kluge:
>
> SELECT Col2, @total := IF(@prev = Col1, @total + Col2, Col2), @prev
> := Col1
> FROM table_name
> ORDER BY Col1;
