I have two databases joined one to many - "customers" and "equipment"

The form shows "customers" information with a portal showing related "equipment".

Customers each get unique serial number generated sequentially as they are added.

As I add records to equipment in the portal, I want to also generate sequential equipment serial numbers 1,2,3 so that I can join the two serial numbers to get unique customer-equipment number that will be used to tie other joined databases.

Example:

Customer "1" has equipment items 1,2,3,4,5 that will be identified as 1-1,1-2,1-3,1-4,1-5.

Customer "2" has equipment items 1,2,3,4,5 that will be identified as 2-1,2-2,2-3,2-4,2-5.

What is the best way to generate sequential serial numbers within a portal that are sequential as above.

Thanks

Use the Last function and add one to it, in auto-enter.

Don't bother. When you delete one it will be all messed up anyway. Instead you can use the @@ symbol to display the row number.