Pony ORM will create our primary key for us automatically if we don’t specify one. To create a foreign key, all you need to do is pass the model class into a different table, as we did in the Album class. Each Required field takes a Python type. Most of our fields are unicode, with one being a datatime object. Next we turn on debug mode, which will output the SQL that Pony generates when it creates the tables in the last statement. Note that if you run this code multiple times, you won’t recreate the table. Pony will check to see if the tables exist before creating them.