Crystal Reports PreviousValue Function

Technical Questions

Crystal Reports Forum : Crystal Reports 9 through 2022 : Technical Questions

Topic: PreviousValue Function

Author	Message
VictorFresno Newbie Joined: 08 Dec 2008 Online Status: Offline Posts: 8	Topic: PreviousValue Function Posted: 08 Dec 2008 at 4:24pm
	How do you reset a PreviousValue formula to for each group change? Because I keep getting a high negative number for my output on the first line of each new group because it's subtracting the Previous Meter Reading from the last group. My formulas are as follows: Group Header Section: whileprintingrecords; numberVar MilesDiff :=0; Details Section: whileprintingrecords; numbervar MilesDiff; MilesDiff := {FTK_MAIN.METER_1} - previous({FTK_MAIN.METER_1}) I don't have anything in the Group Footer, though I tried that earlier and still got the same results. Any help is greatly appreciated! Thanks!
	IP Logged


lockwelle Moderator Joined: 21 Dec 2007 Online Status: Offline Posts: 4374	Posted: 09 Dec 2008 at 7:02am
	I haven't used previous in my reports, but what I would try is putting a flag in the Group Header Section stating a change, then in the Details Section check the flag, if set, skip the calculation and resest the flag. The next record through would use the calculation. Also, it seems that you are trying to reset the MilesDiff variable, if so, it should be declared as Shared numberVar in both sections... OR Group Header Section: whileprintingrecords; shared booleanVar newGroup := true; Details Section: whileprintingrecords; numberVar MilesDiff :=0; shared booleanVar newGroup; if not newGroup then MilesDiff := {FTK_MAIN.METER_1} - previous({FTK_MAIN.METER_1}) else newGroup := false; MilesDiff Lots of ways. Hope that one of them helps
	IP Logged

VictorFresno Newbie Joined: 08 Dec 2008 Online Status: Offline Posts: 8	Posted: 09 Dec 2008 at 8:31am
	Thanks for the feedback Lockwelle! I tried the suggested changes, but received the following error: "A Number is required here" for the following line: else newGroup := false;
	IP Logged

lockwelle Moderator Joined: 21 Dec 2007 Online Status: Offline Posts: 4374	Posted: 09 Dec 2008 at 8:41am
	Sorry, yeah, crystal wants consistency. Change the booleanVar to a numberVar Group Header Section: whileprintingrecords; shared booleanVar newGroup := true; Details Section: whileprintingrecords; numberVar MilesDiff :=0; shared numberVar newGroup; if newGroup = 0 then MilesDiff := {FTK_MAIN.METER_1} - previous({FTK_MAIN.METER_1}) else newGroup := 0;
	IP Logged

VictorFresno Newbie Joined: 08 Dec 2008 Online Status: Offline Posts: 8	Posted: 09 Dec 2008 at 9:10am
	Got an error because of the discrepancy in Shared Variable Types.
	IP Logged

lockwelle Moderator Joined: 21 Dec 2007 Online Status: Offline Posts: 4374	Posted: 09 Dec 2008 at 9:12am
	sorry, follow the consistency and change the booleanVar in the group header to numberVar.
	IP Logged

VictorFresno Newbie Joined: 08 Dec 2008 Online Status: Offline Posts: 8	Posted: 09 Dec 2008 at 9:23am
	Gotcha! It worked like a charm! Thank you very much!
	IP Logged

Printable version

Forum Jump

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum