For what it's worth, Oracle 8.1.6 (and, I'm sure, earlier versions)
supported:

INSERT .... VALUES (...) RETURNING expr... INTO var...

It does not support INSERT ... SELECT with RETURNING.
(single row only).

UPDATE ... RETURNING expr... INTO var...

Is also supported for a single row update. The documentation implies
it is supported for a multi-row update, but that it returns a single
set of values. (Dang if I understand what they are trying to get
at ... I tried a few varients of the INSERT statement and found their
syntax diagrams were just plain WRONG! So I don't know how much I
trust the Oracle docs...)

One advantage of following Oracle syntax is that you can be sure they
will campaign to have it approved by a future edition of the SQL
standard.


Dave