Compare Summary or RunningTotal with the previous group

[Gus01]

Hello,
Is there a simple way to compare the sum of a field with the sum of the same field the previous group (like previous() on a simple record) ?

Ex:
group fld1

2006 100
2006 110
2006 120

2007 200
2007 210

-> Sum (fld1, 2007) - sum (fld1, 2006) = (100 +110 +120) - (200 + 210)

And I must also hide the 1st group (2006) ...
Thank you for your help;

 

[lbass]

You could insert a separate running total of each where you specify the group instance in a formula in the evaluation section:

{table.yeargroup} = 2007 //or 2006

Then you could create a formula:

{#sum2007}-{#sum2006}

Another approach would be to create a formula like this to be placed in a group section, which would always subtract the current group sum from the previous group sum:

whileprintingrecords;
numbervar prev;
numbervar curr;
prev := curr;
curr := sum({table.fld1},{table.yeargroup});
curr-prev

-LB

 

[Gus01]

Thank you for your reply.
I understand the principle and found a solution that works