How can I update or import my database in digital ocean?

I am new to digital ocean, I have a project in django (python) that has already been uploaded, previously it saved data without problems. I did an update and when saving data it sends me errors like:

relationship “Customers_representative” does not exist LINE 1: INSERT IN “Customers_representative” (“representative”, "na…

I guess the problem is with the database, I was told by a developer that I have to import the database into Digital Ocean My question is as follows:

• How do I import my database to my project?

• Do I have to hire a service to host the database and update it there?

• Why did it work before and save data without contracting the database service and now it doesn’t?

Thank you