Re: is there an immutable function to switch from date to character?

On Thu, Apr 25, 2024 at 7:31 AM Celia McInnis <celia(dot)mcinnis(at)gmail(dot)com>
wrote:

> create temporary table junk as select now()::date as evtdate;
>
> alter table junk add column chardate text GENERATED ALWAYS AS
> (to_char(evtdate,'YYYY-Mon-DD')) STORED;
>
> ERROR: generation expression is not immutable
>
> Maybe this is a hack but..

b2bcreditonline=# create temporary table junk as select now()::date as
evtdate;
SELECT 1
b2bcreditonline=# alter table junk add column chardate text GENERATED
ALWAYS AS (to_char(evtdate,'YYYY-Mon-DD')) STORED;
ERROR: generation expression is not immutable
b2bcreditonline=# create or replace function date_to_text(i_date in date)
returns text immutable language sql as $$ select to_char(i_date,
'YYYY-MM-DD') $$;
CREATE FUNCTION
b2bcreditonline=# alter table junk add column chardate text GENERATED
ALWAYS AS (date_to_text(evtdate)) STORED;
ALTER TABLE
b2bcreditonline=# select * from junk;
evtdate | chardate
------------+------------
2024-04-24 | 2024-04-24
(1 row)