Not sure how up to date the SQL above is for this problem. Below is the SQL I had to use to fix a naming problem for users as we moved from one LDAP service to another (their 6+2 login names were slightly different in some cases).
begin
for i in (select * from usermigration)
loop
delete from external_entities
where name = i.newusername;
update external_entities
set name = i.newusername
where name = i.oldusername;
update attachments
set creator = i.newusername
where creator = i.oldusername;
update attachments
set lastmodifier = i.newusername
where lastmodifier = i.oldusername;
update content
set lastmodifier = i.newusername
where lastmodifier = i.oldusername;
update content
set creator = i.newusername
where creator = i.oldusername;
update content
set username = i.newusername
where username = i.oldusername;
update content_label
set owner = i.newusername
where owner = i.oldusername;
update draft
set owner = i.newusername
where owner = i.oldusername;
update extrnlnks
set creator = i.newusername
where creator = i.oldusername;
update extrnlnks
set lastmodifier = i.newusername
where lastmodifier = i.oldusername;
update links
set lastmodifier = i.newusername
where lastmodifier = i.oldusername;
update links
set creator = i.newusername
where creator = i.oldusername;
update notifications
set username = i.newusername
where username = i.oldusername;
update notifications
set lastmodifier = i.newusername
where lastmodifier = i.oldusername;
update notifications
set creator = i.newusername
where creator = i.oldusername;
update pagetemplates
set lastmodifier = i.newusername
where lastmodifier = i.oldusername;
update pagetemplates
set creator = i.newusername
where creator = i.oldusername;
update spaces
set creator = i.newusername
where creator = i.oldusername;
update spaces
set lastmodifier = i.newusername
where lastmodifier = i.oldusername;
update spacepermissions
set permusername = i.newusername
where permusername = i.oldusername;
update spacepermissions
set creator = i.newusername
where creator = i.oldusername;
update spacepermissions
set lastmodifier = i.newusername
where lastmodifier = i.oldusername;
update contentlock
set creator = i.newusername
where creator = i.oldusername;
update contentlock
set lastmodifier = i.newusername
where lastmodifier = i.oldusername;
--update emailtemplates
--set creator = i.newusername
--where creator = i.oldusername;
--update emailtemplates
--set lastmodifier = i.newusername
--where lastmodifier = i.oldusername;
--update emailtemplates
--set username = i.newusername
--where username = i.oldusername;
update os_user
set username = i.newusername
where username = i.oldusername;
update trackbacklinks
set creator = i.newusername
where creator = i.oldusername;
update trackbacklinks
set lastmodifier = i.newusername
where lastmodifier = i.oldusername;
update OS_PROPERTYENTRY
set entity_name = replace(entity_name,i.oldusername,i.newusername)
where entity_id = (select entity_id from external_entities where entity_name = i.newusername);
end loop;
end;