How to add fields to existing tables
* https://www.postgresql.org/docs/current/sql-altertable.html
* https://www.sqlite.org/lang_altertable.html
* https://dev.mysql.com/doc/refman/8.0/en/alter-table.html

Peewee can help you. If you had looked at the docs, you'd probably have found it:

http://docs.peewee-orm.com/en/latest/peewee/playhouse.html#migrate This kind of question belongs on stack overflow. NOT on the issue tracker. Please use your brain.
For example, now I have created a model and executed to create a table. Then I want to add fields to this table. What should I do?