how to calculate the difference

[jmd0252]

OK I have a meter readings file, to keep it simple. Date and meter reading. So I got say 6 records,, How on the crystal report do I calculate the difference,,from one meter reading to the next..

file would look like this
2009/01/01 123456
2009/02/01 123987
2009/03/01 124025

Ideas,, suggestions,, solutions..

 

[lbass]

Create a formula like this:

if not onfirstrecord then
{table.value}-previous({table.value})

-LB

 

[jmd0252]

ohhhhhhhhh,,, that works nicely,,, now,

The readings are "group", by account, so how do I get it to calculate it within the group only,, and not keep going?? The calculation needs to "reset". each time the group changes.

 

[lbass]

if not onfirstrecord and
{table.groupfield} = previous({table.groupfield}) then
{table.value}-previous({table.value})

-LB

 

[jmd0252]

Outstanding simplely outstanding,, where did you find the "previous"??

 

[lbass]

It was two rows behind the "next" . Look in the functions list in the formula editor->print state->previous. You can learn a lot about CR just by scrolling through the functions list and checking out the related Help files.

-LB