Firebird Documentation Index → Firebird 2.1 Language Ref. Update → Context variables → 'NOW' |
Find a more recent version at Firebird 5.0 Language Reference: 'NOW'
Available in: DSQL, PSQL, ESQL
Changed in: 2.0
Description: 'NOW'
is not a variable but a string literal. It is, however,
special in the sense that when you CAST() it to a date/time type, you
will get the current date and/or time. The fractional part of the time used to be always
“.0000
”, giving an effective seconds precision. Since
Firebird 2.0 the precision is 3 decimals, i.e. milliseconds. 'NOW'
is
case-insensitive, and the engine ignores leading or trailing spaces when casting.
Type: CHAR(3)
Examples:
select 'Now' from rdb$database -- returns 'Now'select cast('Now' as date) from rdb$database -- returns e.g. 2008-08-13select cast('now' as time) from rdb$database -- returns e.g. 14:20:19.6170select cast('NOW' as timestamp) from rdb$database -- returns e.g. 2008-08-13 14:20:19.6170Shorthand syntax for the last three statements:
select date 'Now' from rdb$database select time 'now' from rdb$database select timestamp 'NOW' from rdb$database
Notes:
'NOW'
always returns the actual date/time, even in PSQL
modules, where CURRENT_DATE
, CURRENT_TIME
and CURRENT_TIMESTAMP
return the same value throughout the duration of the outermost routine. This makes
'NOW'
useful for measuring time intervals in triggers, procedures
and executable blocks.
Except in the situation mentioned above, reading
CURRENT_DATE
, CURRENT_TIME
and CURRENT_TIMESTAMP
is generally preferable to casting 'NOW'
. Be aware though that
CURRENT_TIME
defaults to seconds precision; to get milliseconds
precision, use CURRENT_TIME
(3
).
Firebird Documentation Index → Firebird 2.1 Language Ref. Update → Context variables → 'NOW' |