On Sat, Apr 26, 2025 at 5:50 AM PG Doc comments form <nore...@postgresql.org> wrote:
> The following documentation comment has been logged on the website: > > Page: https://www.postgresql.org/docs/17/dml-returning.html > Description: > > Today I found a pretty special use-case for the "RETURNING" functionality, > which I cannot find documentation for? > If you have a statement as follows: > UPDATE persons SET name = 'Bob' WHERE id = 4 > RETURNING (SELECT name FROM persons WHERE id = 4) > The returning data will be whatever the value was before the row was > modified. This differs from if I were to "RETURNING name". I found this to > be interesting and could possibly warrant some kind of explanation in the > documentation? > > I would not want to encourage that form of query. The novelty is more problematic than the brevity. Plus, repetition. with new_p as ( update persons set name = 'Bob' returning name where id = 4) select old_p.id as id, old_p.name as old_name, new_p.name as new_name from persons as old_p join new_p on new_p.id = old_p.id And now that we actually allow references to "new" and "old" in v18 that form is also obsolete and you can do this directly. David J.
