How do I insert a record and put the ID into an existing record in another table?

I want to insert a record in one table and save the resuting ID in a record I already have in another table. Which sounds easy. Simplistic example: create table aaa (id serial primary key, foo int); create table foos (id serial primary key, foo int, aaa_id int); Imagine foos has rows which I want to insert in aaa. But I want a record of aaa.id stored in foos.aaa_id. Heres some code that definitely does not work: with rows as ( insert into aaa (foo) select foo from foos returning foos.id as foos_id, aaa.id as aaa_id ) update foos set aaa_id = (select aaa_id from rows where foos_id = foos.id); I can't find a way of getting the "returning" clause to return anything other than records from the table it inserted. Surely there must be a simple way to do this?