I have had some issues regarding the gui not beeing updated after I create a campaign or discount via code. Where can I find the campaign and discounts in the databse? The promotions/campaign tables seems empty to me so where does epi save them?
Promotions are stored in the cms database together with other content, in tblContentType. :) And the values are stored just as cms values in the tblContentProperty.
Edit: This is the "new" promotion system introduced in Commerce 9.24.
We don't disclose on how data is saved in database. If you have problem with data is not being shown in UI, then you can post your code here and we might spot the problem. Also, it would help if you state your versions, and which promotion system you are using (the new or the legacy one, as Joel commented)