> Because it has no way to target a specific row in a specific table,
> as it can with a regular join.

If I could use aliases maybe ibo could figure out the rest, or maybe
if I could edit the sql used for singleton select.

> You can't use KeyRelation to make a self-referencing join query
> updatable. KeyRelation absolutely requires to be able to target a
> unique row in the underlying KeyRelation member. Your flat
> structure doesn't allow this.

If I enable FetchWholeRows and disable sync after edit and post, so I
tell ibo not to try and run singleton select then it works, the query
is live. But I guess this is just a "side effect"/feature/"wrong
using" or whatever you want to call it.

> There are various ways you could implement an updatable structure
> out of this relationship.
> ...

Thank you for that information. It help me better understand ibo
internals. Method 3 is ok for me. Or I could create a view (but not
updatable as I only want to get the boss name from table person and if
the join doesn't have to tables with the same name then is ok:
create view boss (id_boss, boss_name)
as select id, name from person
and then just:
SELECT
p.*,
b.boss_name
FROM
person p
inner join boss b
on p.id_boss = b.id_boss

Thanx again for the info.