Reset counter in subform

[huzefahashim]

Hi,
I am trying to make a database for invoices generated. Within each
invoice, is another table with the invoice details. Both tables are
linked. When a user enters data for an invoice, I would like the
subform (the invoice details) to enter the counter for each new
record.
For example, Invoice A has 3 items and Invoice B has 5 items. When the
user enters Invoice A and enters those 3 items within the form, there
is an autonumber which shows the numbers 1 to 3 (or more, if there are
more entries.
When the user starts entering data for Invoice B, the counter starts
from 4 (because there are already 3 items in the 'Invoice Details'
table. How can I set it to start the counter from 1 everytime a new
invoice is being created?

 

[storrboy]

If the numbers staying in order is important, don't use AutoNumber.
You'll have to make your own incremental number system. Autonumbers
are not intended to mean anything. By definition they are
*auto*matically generated, not constantly manipulated or customized.

 

[huzefahashim]

If the numbers staying in order is important, don't use AutoNumber.
You'll have to make your own incremental number system. Autonumbers
are not intended to mean anything. By definition they are
*auto*matically generated, not constantly manipulated or customized.

And how do I do that? i.e. make my own incremental number system?

 

[storrboy]

You'd have to create a method of determining the last number used and
incrementing it by a determined amount. The exact method may be
dependant on the circumstances, but it could be as simple as creating
a function that uses the DMax function to get the largest number used
in a table, adding one and assigning the new number to the record
currently being saved.