BUG #18542: Order by expression, that contains column from projection isn't working
The following bug has been logged on the website:
Bug reference: 18542
Logged by: Aleksandr Novozhilov
Email address: ivningman@gmail.com
PostgreSQL version: 16.1
Operating system: Windows
Description:
select z as y from
(select 1 as z) x
order by y + 1
That query finishes with error:
ERROR: column "y" does not exist
Position: 48
But wrapping it with select works fine:
select * from (select z as y from
(select 1 as z) x) c
order by y + 1
PG Bug reporting form <noreply@postgresql.org> writes:
select z as y from
(select 1 as z) x
order by y + 1
That query finishes with error:
ERROR: column "y" does not exist
Position: 48
But wrapping it with select works fine:
select * from (select z as y from
(select 1 as z) x) c
order by y + 1
This is not a bug. See
https://www.postgresql.org/docs/current/queries-order.html
particularly "Note that an output column name has to stand alone, that
is, it cannot be used in an expression". The fact that we allow this
at all is a hangover from SQL92; per SQL99 and later, variables in
ORDER BY should refer to input columns (that is, outputs of the FROM
clause).
regards, tom lane