Docker-web application

Assume that I have one Web application that starts in tomcat and getting database connection properties from file. Once it started it connects to the DB and this DB present in my local hard disk.

If i would use the docker then i need to create the war file first that can might be done through docker or other tool also, but once will deploy to the tomcat as a container then how to do? also when it will be started how to provide the database.propeties file to be read. Should we require to create the DB in separate container or it would be good to keep the DB in local only. what is the drawback of not keeping the DB as in a container?
As it can keep large records so if i use container then it will store somewhere in container or in my local machine?

Please help me in all these in details.