INSERT INTO ... RETURNING multiple columns (PostgreSQL)

Question

I've searched around for an answer and it seems definitive but I figured I would double check with the Stack Overflow community:
Here's what I'm trying to do:

INSERT INTO my_table VALUES (a, b, c)
RETURNING (SELECT x, y, z FROM x_table, y_table, z_table
WHERE xid = a AND yid = b AND zid = c)

I get an error telling me I can't return more than one column.
It works if I tell it SELECT x FROM x_table WHERE xid = a.

Is this at all possible in a single query as opposed to creating a seperate SELECT query?

I'm using PostgreSQL 8.3.

Answer 1

Try this.

with aaa as (
    INSERT INTO my_table VALUES(a, b, c)
    RETURNING a, b, c)
SELECT x, y, z FROM x_table, y_table, z_table
WHERE xid = (select a from aaa)
  AND yid = (select b from aaa)
  AND zid = (select c from aaa);

In 9.3 similar query works.

Answer 2

@corvinusz answer was wrong for 8.3 but gave me a great idea that worked so thanks!

INSERT INTO my_table VALUES (a, b, c)
RETURNING (SELECT x FROM x_table WHERE xid = a),
  (SELECT y FROM y_table WHERE yid = b),
  (SELECT z FROM z_table WHERE zid = c)

I have no idea why the way it's stated in the question is invalid but at least this works.