Apache mysql adminer docker container with same network

docker-compose.yml

version: "3"
services:

  web:
    build: ./web/
    volumes:
      - ./app/:/var/www/html/
    ports:
      - 8000:80
    networks: 
      - backend
  db:
   image: mysql
   container_name: mysqlserver
   command: --default-authentication-plugin=mysql_native_password
   restart: always
   networks: 
    - backend

   environment:
     MYSQL_ROOT_PASSWORD: kazdal

  adminer:
    image: adminer
    restart: always
    networks: 
      - backend
    ports:
      - 8080:8080
networks:
  backend:
    driver: bridge