How to open port for docker container?

Question

LXC

There is a fighting machine with a database, and there is a container with a web server and cgi.
Forwarding the port from the container to localhost is understandable, -p=80:80
And docker port will show 80/tcp ->
0.0.0.0:80 to give the database port of the combat server to the docker container is not entirely clear.
How do you do it? What are the ways?
PS The "docker" tag doesn't exist?

Answer 1

stackoverflow.com/questions/24319662/from-inside-o...
but it would be better to run mysql in a container too