Select
Extract(Day From current_date)
, Extract(Month From current_date)
, Extract(Year From current_date)
from rdb$database;
CURRENT_DATE CURRENT_TIMESTAMP
13.01.2009 13.01.2009 19:28
Select
Extract(Day From current_date)
|| ‘-’
|| Extract(Month From current_date)
|| ‘-’
|| Extract(Year From current_date)
from rdb$database;
-> 13-1-2009
There are two variables available, CURRENT_DATE which returns the current date and CURRENT_TIMESTAMP which returns date and time. You can use those in SQL statements:
insert into t1 values(10, CURRENT_TIMESTAMP);
To query the current time, use this:
Select current_date, current_timestamp
from rdb$database;
You need to select from something and rdb$database is a convenient one-row table that is present in each database.
You can also assign those variables in PSQL (stored procedure and trigger language):
create procedure p1
as
BEGIN
if (current_timestamp > cast(‘2007-11-03′ as timestamp)) then
exception myerror;
…
END
It should be noted that CURRENT_TIMESTAMP returns the timestamp of transaction start, which means it is constant during the transaction. If you need the exact timestamp of that very moment, use a special value ‘now’. It’s a char(3) string, so you need to cast it to timestamp explicitly.
select cast(‘now’ as timestamp), cast(‘today’ as date)
from rdb$database
As you can see, the same rule applies for CURRENT_DATE, and you can use a special value ‘today’, to get the current value.
The reason behind all this is that transactions should be atomic, so CURRENT_DATE and CURRENT_TIMESTAMP provide consistency. Especially in 24/7 systems it can easily happen that the date changes between transaction start and end.
If you have time values, just subtract them, and you’ll get the interval length in seconds:
select end_time – start_time
from …
If you want to get minutes, divide the result by 60, and if you want hours by 3600.
If you have timestamps instead of times, the difference is in days, so you if you want seconds, you need to multiply the value by 60 * 60 * 24.
