From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of salah jubeh Sent: Wednesday, December 21, 2011 6:39 AM To: pgsql Subject: [GENERAL] can not use the column after rename
Hello,
Why I can not do something like this in Postgres.
SELECT 1 as a , 2 as b , a + b as c ;
Regards
In a declarative language same-level cross-references are difficult to process (though admittedly not impossible). What if you had written:
SELECT a + b AS c, 1 as a, 2 as b
If scanned in a linear (top-to-bottom) fashion A and B would not be defined at the time the “a + b” part was evaluated.
