如何结合这两个Postgresql查询？

Question

I want to insert into a first table, then update a second table with the returned (DB generated) UUID of the inserted row before finally returning the result of the insert.

The insert query looks like this:

INSERT INTO public.organisations ("name")
VALUES('StackOverflow')
RETURNING *

This will return a row with name, data and id. Data is an empty JSON and can be ignored, id is the UUID used below.

The update query looks like this, with <orgId> indicating the UUID generated and returned by the above insert and <userId> indicating a value passed in from code:

UPDATE public.users
SET id_organisation = <orgID>, last_modified_by = <userID>
WHERE id = <userID>;

Both of these queries work but I do not know how to string them together and return the output of the first query.

Is it possible to do this or would I be better just running two queries?

Answer 1

Use CTEs:

with i as (
      INSERT INTO public.organisations ("name")
          VALUES('StackOverflow')
          RETURNING *
     )
UPDATE public.users
    SET id_organisation = (SELECT i.id FROM i LIMIT 1),        last_modified_by = <userID>
    WHERE id=<userID>;

Note that this uses a subquery with LIMIT -- this guarantees that at most one row is returned.

Here is a db<>fiddle illustrating that the syntax works.