Hannes Dorbath írta:
Joshua D. Drake wrote:
postgres=# SELECT current_date|| ' a ' || to_char(current_date, 'Day'),
current_date + '1 Year'::interval || ' a ' || to_char(current_date +
'1 Year'::interval, 'Day') as next_birthday;
?column? | next_birthday
------------------------+---------------------------------
2008-05-04 a Sunday | 2009-05-04 00:00:00 a Monday
?
Sorry, I think I phrased the question badly. What I'm after basically is:
http://www.depesz.com/index.php/2007/10/26/who-has-birthday-tomorrow/
If you define the same functional index as in the above link:
CREATE OR REPLACE FUNCTION indexable_month_day(date) RETURNS TEXT as $BODY$
SELECT to_char($1, 'MM-DD');
$BODY$ language 'sql' IMMUTABLE STRICT;
create table user_birthdate (
id serial not null primary key,
birthdate date
);
create index user_birthdate_day_idx on user_birthdate (
indexable_month_day(birthdate) );
Then you can use this query:
select count(*) from user_birthdate where indexable_month_day(birthdate)
> '02-28' and indexable_month_day(birthdate) <= '03-01';
In a generic and parametrized way:
select * from user_birthdate
where
indexable_month_day(birthdate) > indexable_month_day(now()::date) and
indexable_month_day(birthdate) <= indexable_month_day((now() + '1
days'::interval)::date);
This will still use the index and it will work for the poor ones
who have birthday every 4 years, too. Assume, it's 02-08 today, 03-01
the next day.
The now() < X <= now() + 1 day range will find 02-29.
--
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Zoltán Böszörményi
Cybertec Schönig & Schönig GmbH
http://www.postgresql.at/
