postgres update return new values and old values

query.sql

-- returning updated values and old values by using a sub-expression

update orders
  set type = 'delivery'
  where id = 3767
  returning id, type, (
    select type from orders where id = 3767
  ) as old_type;

Thank you very much. I owe you a beer.

Thanks，this SQL works for me

This will only work if isolation level is higher than 'read uncommitted', won't work with 'read uncommitted' setting.

So in case of concurrent DB transactions, we are safe to get the last value for this particular update if the Isolation Level is "Read committed" ?

How does this make it ?

I just asked CHATGPT and it showed the same way as the gist showes, also it's okay to use with clause to make temp table to store the old values or use triggers with OLD keyword , but I think the subquery one is the most convenient way.