referencing previous record

[ggg3ggg]

How do you go about subtracting the value of the previous field from todays field.

ie: if field is temp
record number is 100 value =33.2
record number is 101 value is 34.5

result required is 34.5-33.2=1.3
tia

 

[Tanis]

Put some code in the After Update event procedure of the second[/i]

 

[ggg3ggg]

Tanis
Could you elaborate- I don't really understand what you mean.

 

[Tanis]

Put some code in the After Update event procedure of the secondcontrol e.g.

Temp = Me.ControlName1 - Me.ControlName2

No error checking here though! You will have to provide that yourself.


David

 

[ggg3ggg]

I think you are WAY above me here-sorry. Are you talking macros?
Can it be done with the formula builder.
I have a little little experience with VBA for excel but none with Access.

 

[Russell Hauf]

What other fields do you have in your query or table? Is there a date field (you mentioned yesterday and today)?

 

[ggg3ggg]

date field and then whole series of temperature (decimal) values

 

[ggg3ggg]

OK thanks
I will give that a try over the weekend.

Enjoy yours!

 

[Russell Hauf]

Ok, I deleted my last post. It was garbage. Here's a better way.

Ok, in your query (in the query design view), right-click on the table that is in your query, and select Properties. Change "Alias" to "X" (no quotes). Then add a field in your query (make sure that your query is sorted ascending by Date) something like this:

Diff: [fldProjNum]-(SELECT fldProjNum from tbl060603b WHERE fldDateIn = (SELECT MAX([fldDateIn]) FROM tbl060603b WHERE [fldDateIn] < X.fldDateIn))

You'll need to change the table and field names - in my query,

tbl060603b is my table
fldProjNum is my "temperature"
fldDateIn is my date

This one does work.

HTH,

Russell