create table {$NAMESPACE}_user.user_oauthinfo (
  id int unsigned not null auto_increment primary key,
  userID int unsigned not null,
  oauthProvider varchar(255) not null,
  oauthUID varchar(255) not null,
  unique key (userID, oauthProvider),
  unique key (oauthProvider, oauthUID),
  dateCreated int unsigned not null,
  dateModified int unsigned not null
);

insert into {$NAMESPACE}_user.user_oauthinfo
  (userID, oauthProvider, oauthUID, dateCreated, dateModified)
  SELECT id, 'facebook', facebookUID, UNIX_TIMESTAMP(), UNIX_TIMESTAMP()
    FROM {$NAMESPACE}_user.user
    WHERE facebookUID is not null;

alter table {$NAMESPACE}_user.user drop facebookUID;