You could try using something like Synth[0]! You can hook it up to a database, it'll generate some json describing the shape and types of your data based on your database (or you could write the json yourself), then you can use Synth to generate fake data and directly insert it into your database.

Full disclosure, I'm the maintainer, but it's not like it'll cost you anything.

[0] https://www.getsynth.com