Hello Daniel,
You don't have to do this manually, in your export template for product_sku field you can create
RO CSVI combine rule to combine product_sku with another field. This another field will be
custom with a default value set in template fields page. Say if the default value set for custom field is 1 and product_sku in database is XXXX, with the combine character set as _ in the rule, the rule will combine these two fields and get a new product_sku field value as XXXX_1 in export file. Let me know if that is clear.
Kind regards,
Tharuna
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