if you use the :from option, you can use the change without explicit declaring up and down:
def change do
alter table(:address) do
modify :person_id, references(:person, on_delete: :nothing),
from: references(:person, on_delete: :delete_all)
end
end
docs: Ecto.Migration — Ecto SQL v3.11.1
This command is not reversible unless the
:fromoption is provided. If the:fromvalue is a%Reference{}, the adapter will try to drop the corresponding foreign key constraints before modifying the type.






















