create_table("customers") {
  t.Column("id", "integer", {primary: true})
  t.Column("first_name", "string", {"size": 255})
  t.Column("last_name", "string", {"size": 255})
  t.Column("email", "string", {})
}

sql("alter table customers alter column created_at set default now();")
sql("alter table customers alter column updated_at set default now();")