Cannot connect Wordpress on external dbgetaddrinfo failed: Name or service not known

I would like to run my Wordpress site on Docker, and I want to connect the Wordpress database to another container which have only the databases of all my sites.

For doing so, I've created a LAMP container using the following docker-compose.yml:

version: "3"

services:
  web: 
    image: webdevops/php-apache:alpine-php7
    ports:
      - "4500:80"
    volumes: 
      - ./www:/app
      - ./uploads.ini:/opt/docker/etc/php/php.ini

  db:
    image: mysql
    command: --default-authentication-plugin=mysql_native_password
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: root
    ports:
      - "3306:3306"

  phpmyadmin:
    image: phpmyadmin/phpmyadmin
    environment:
      MYSQL_ROOT_PASSWORD: root
    ports:
      - "8088:80"

as you can see I've installed Apache as service using the webdevops image, this return the following:

Then, I've created a new container which have the Wordpress instance:

version: '3'

    services:
      wordpress:
       depends_on:
         - db
       image: wordpress:latest
       volumes:
         - ./wp/wp-content:/var/www/html/wp-content
       ports:
         - "8000:80"
       restart: always
       environment:
         WORDPRESS_DB_HOST: lamp_db_1:3306
         WORDPRESS_DB_USER: root
         WORDPRESS_DB_PASSWORD: root
    
    volumes:
      dbdata:
      wp-content:

as you can see I mount the wp-content folder since I already have a Wordpress installation with plugins and media... then I tried to connect this container to lamp_db_1 container but when I run this using:

docker-compose up --build

I get:

MySQL Connection Error: (2002) php_network_getaddresses: getaddrinfo failed: Name or service not known

what I did wrong?

How can I connect the wordpress container to the LAMP container?

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