MySql in DNX 5.0
Saldy it's not in EntityFramework 7 yet, my understanding is that they're not prioritizing it for the initial release that's scheduled in January.
Read more:https://github.com/aspnet/EntityFramework/wiki/Using-EF7-in-Traditional-.NET-Applications
I have a similar question running.
DNXCORE 5.0 and mysql / mariadb
At this moment it is not possible to run MySQL and DNX 5.0! If you want to use it with DNX, you have to fall back on 4.5.1 ( and use mono for Linux environments )
This is because there is no connector available for MySQL. If applicable, you can use postgresql with DNX 5.0 in stead of MySQL/MariaDB