Parent/Child relation without ID PK?

[DevGiu]

Hi,

I have 2 tables.
Table 1:
id
code
name
company

table 2:
id
code
table1code
company

The problem is, I want to reference table2->table1code with table1->code, not with table1->id, and AppGini forces me to link over ID PK.
For optimization, MySQL has autonumeric, but if I reference with this, I enter into problems importing/exporting data. For example, If I try to export invoices, and try to import on another instance of the application, autonumeric could be different, and I will lose the reference between parent/child.
For this reason, I need to have a stable value to reference.

Maybe I have my mind locked, and probably there are something obvious I don't see right now (for sure, too much hours working this week) but I don't see any efficient way to do this.