Prisma generates database tables with uppercase in mysql. Is there any way to generate tables only in lowercase?

At the moment you have to do that manually with @map and @@map.

You can read more about this here.

Here an example:

model PostInCategories {
  category Category @map(name: "category_id")
  post     Post     @map(name: "post_id")

  @@unique([post, category], name: "post_id_category_id_unique")
  @@map(name: "post_in_categories")
}