prismaBasicOperation.ts

// Firstly, we need a schema file to model the database
generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL") // the DATABASE_URL is stored in .env file
}

model Cat {
  id            Int         @default(autoincrement()) @id
  name          String
  age           Int
  breed         String   
}

// To generates SQL files and also runs them on the configured database, run following command
 npx prisma migrate dev --name init

// Create a Database service to interact with the Prisma Client API
@Injectable()
export class PrismaService extends PrismaClient implements OnModuleInit {
  async onModuleInit() {
    await this.$connect();
  }

  async enableShutdownHooks(app: INestApplication) {
    this.$on('beforeExit', async () => {
      await app.close();
    });
  }
}
// In service layer, we inject the DatabaseService
constructor(private prisma: PrismaService) {}

// We can perform database operation via Prisma client api as below
// Please note that we use Prisma Client’s generated types, like the "Cat"
  async cat(
    catWhereUniqueInput: Prisma.CatWhereUniqueInput,
  ): Promise<Cat | null> {
    return this.prisma.cat.findUnique({
      where: catWhereUniqueInput,
    });
  }