8.4. Date and Time Functions - 8.4.1. DATEADD() - 《Firebird 2.5 Language Reference》

8.4.1. DATEADD()

8.4.1. `DATEADD()`

Available in

DSQL, PSQL

Changed in

2.5

Syntax

DATEADD (<args>)
<args> ::=
    <amount> <unit> TO <datetime>
  | <unit>, <amount>, <datetime>
<amount> ::= an integer expression (negative to subtract)
<unit> ::=
    YEAR | MONTH | WEEK | DAY
  | HOUR | MINUTE | SECOND | MILLISECOND
<datetime> ::= a DATE, TIME or TIMESTAMP expression

Table 141. `DATEADD` Function Parameters
Parameter	Description
amount	An integer expression of the `SMALLINT`, `INTEGER` or `BIGINT` type. A negative value is subtracted
unit	Date/time unit
datetime	An expression of the `DATE`, `TIME` or `TIMESTAMP` type

Result type

DATE, TIME or TIMESTAMP

Description

Adds the specified number of years, months, weeks, days, hours, minutes, seconds or milliseconds to a date/time value. (The WEEK unit is new in 2.5.)

The result type is determined by the third argument.
With TIMESTAMP and DATE arguments, all units can be used. (Prior to Firebird 2.5, units smaller than DAY were disallowed for DATEs.)
With TIME arguments, only HOUR, MINUTE, SECOND and MILLISECOND can be used.

Examples

dateadd (28 day to current_date)
dateadd (-6 hour to current_time)
dateadd (month, 9, DateOfConception)
dateadd (-38 week to DateOfBirth)
dateadd (minute, 90, time 'now')
dateadd (? year to date '11-Sep-1973')