eval.sql

CREATE FUNCTION eval(sql Text) RETURNS SETOF Record AS $$
    BEGIN
        RETURN QUERY EXECUTE sql;
        RETURN;
    END;
$$ LANGUAGE plpgsql;

SELECT * FROM eval('SELECT * FROM( VALUES (1), (3) ) AS t') AS (i Int);

 i
---
 1
 3
(2 rows)

SELECT * FROM eval('SELECT * FROM( VALUES (1,''a''), (3,''b'') ) AS t') AS (i Int, c Text);

 i | c
---+---
 1 | a
 3 | b
(2 rows)