Create a project with

bun init .

Edit package.json: version, description, etc.

Install packages:

bun i express morgan cors
bun i -D @types/express @types/cors @types/morgan prisma

Initialize Prisma:

bunx prisma init --datasource-provider sqlite

Check that .gitignore contains .env (it should with Bun).

Edit schema.prisma to add the Forum entity:

model Forum {
   id        Int      @id      @default(autoincrement())
   name      String   @unique
   createdAt DateTime @default(now())
}

Push the schema.prisma to the database to apply changes:

bunx prisma db push

Open Prisma Studio (bunx prisma studio) and add a couple of Forums to check.

Add two more entities: User and Message.

model User {
   userId    Int       @id @default(autoincrement()) @map("id")
   nick      String    @unique
   fullName  String?
   createdAt DateTime  @default(now())
   admin     Boolean   @default(false)
   messages  Message[]
}

model Message {
   id      Int    @id @default(autoincrement())
   text    String
   userId  Int
   User    User   @relation(fields: [userId], references: [userId])
   forumId Int
   Forum   Forum  @relation(fields: [forumId], references: [forumId])
}

Push changes in the schema to the database.

Create a prisma/seed.ts file and add test data that you would like to have in the initial database (after a reset).

Add the "prisma" section to the package.json file to invoke the seeding process:

{
  // ...
  "prisma": {
    "seed": "bun prisma/seed.ts"
  }
}

Now reset the database to check that it can be re-created from scratch:

rm prisma/dev.db
bunx prisma db push
bunx prisma db seed