As we've already seen, the purpose of our Media schema is to represent the data that we retrieve from the database in the Elixir world. Since we are using a relational database, data is persisted in database tables.
To create the tables, instead of executing a SQL script directly on the database, we will use Ecto migrations to apply every database schema change for us.
Migrations live on the priv/repo/migrations folder as Elixir scripts and their name should abide by the <timestamp>_<snake_case_name>.exs format, for example 20180112095312_create_media.exs. To execute a migration or roll back an existing one, you should use ecto.migrate or ecto.rollback, respectively.
Here's the CreateMedia migration responsible for the creation ...
