'NOW'

`'NOW'`

Current date and/or time in cast context

Type

CHAR(3), or depends on explicit CAST

'NOW' is not a variable, but a string literal or datetime mnemonic.It is, however, special in the sense that when you CAST() it to a datetime type, you will get the current date and/or time.If the datetime type has a time component, the precision is 3 decimals, i.e. milliseconds.'NOW' is case-insensitive, and the engine ignores leading or trailing spaces when casting.

Note

'NOW' always returns the actual date/time, even in PSQL modules, where [fblangref50-contextvars-current-date], [fblangref50-contextvars-current-time] and [fblangref50-contextvars-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 [fblangref50-contextvars-current-date], [fblangref50-contextvars-current-time] and [fblangref50-contextvars-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 3.0 and earlier allowed the use of 'NOW' in datetime literals (a.k.a. "`shorthand casts"`), this is no longer allowed since Firebird 4.0.

Examples

select 'Now' from rdb$database
-- returns 'Now'

select cast('Now' as date) from rdb$database
-- returns e.g. 2008-08-13

select cast('now' as time) from rdb$database
-- returns e.g. 14:20:19.6170

select cast('NOW' as timestamp) from rdb$database
-- returns e.g. 2008-08-13 14:20:19.6170

`OLD`

Record with the initial values of a row before update or delete

Available in

PSQL — triggers only,
DSQL — RETURNING clause of UPDATE, UPDATE OR INSERT and MERGE

Type

Record type

Syntax

OLD.column_name

Table 1. `OLD` Parameters
Parameter	Description
column_name	Column name to access

OLD contains the existing version of a database record just before a deletion or update.The OLD record is read-only.

Note	In multi-action triggers `OLD` is always available.However, if the trigger is fired by an `INSERT`, there is obviously no pre-existing version of the record.In that situation, reading from `OLD` will always return `NULL`.