update contacts
  set birthday = substr(birthday, 3, 2) || '-' || substr(birthday, 5, 2)
  where birthday GLOB '--[01][0-9][0-3][0-9]';

update contacts
  set birthday = substr(birthday, 1, 4) || '-' || substr(birthday, 5, 2) || '-' || substr(birthday, 7, 2)
  where birthday GLOB '[0-9][0-9][0-9][0-9][01][0-9][0-3][0-9]';