How to run a MySQL command terminal in Docker, with a docker-compose server

Let's say I have the following compose file :

networks:
  my_network:

services:

  ...

  mysql:
    container_name: "mysql"
    image: "mysql:5.7"
    volumes:
      - ./mysql.cnf:/etc/mysql/conf.d/mysql.cnf
    environment: 
      MYSQL_ROOT_PASSWORD: "password"
      MYSQL_USER: "user"
      MYSQL_PASSWORD: "password"
      MYSQL_DATABASE: "test-db"
    ports:
      - "3306:3306"
    restart: always
    networks: 
      - my_network

Once I run docker-compose up, my services get started and I can see that my MySQL server is ready to accept connections. Now what do I need to do to access the mysql terminal prompt from "outside" the container ? I remember seeing a teacher run another docker container (from a new terminal), and access the MySQL command prompt, enabling him to manage the database by hand, from another terminal window, but I can't remember the command exactly.

I tried running a new Docker container like this :

docker run -it --rm --name mysqlterm \
  --network="compose_project_my_network" \
  --link mysql mysql:5.7 \
  sh -c 'exec mysql \
  -h "localhost" -P 3306" \
  -uroot \
  -ppassword'

But unfortunatly, the container can't connect to the MySQL server, giving me the following error : ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2).

I guess the "localhost" or 3306 port are wrong ? What should I put in these parameters ?

Thanks in advance for your answers :)

Copyright Notice：Content Author:「souyahia」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/61747708/how-to-run-a-mysql-command-terminal-in-docker-with-a-docker-compose-server