Date Functions
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This section describes functions and operators for examining and manipulating date values.
The table below shows the available mathematical operators for DATE types.
Operator
Description
Example
Result
+addition of days (integers)
DATE '1992-03-22' + 51992-03-27
+addition of an INTERVAL
DATE '1992-03-22' + INTERVAL 5 DAY1992-03-27
+addition of a variable INTERVAL
SELECT DATE '1992-03-22' + INTERVAL (d.days) DAY FROM (VALUES (5), (11)) AS d(days)1992-03-27 and 1992-04-02
-subtraction of DATEs
DATE '1992-03-27' - DATE '1992-03-22'5
-subtraction of an INTERVAL
DATE '1992-03-27' - INTERVAL 5 DAY1992-03-22
-subtraction of a variable INTERVAL
SELECT DATE '1992-03-27' - INTERVAL (d.days) DAY FROM (VALUES (5), (11)) AS d(days)1992-03-22 and 1992-03-16
Adding to or subtracting from infinite values produces the same infinite value.
The table below shows the available functions for DATE types.
Dates can also be manipulated with the timestamp functions through type promotion.
Name
Description
current_dateCurrent date (at start of current transaction).
date_add(date, interval)Add the interval to the date.
date_diff(part, startdate, enddate)The number of partition boundaries between the dates.
date_part(part, date)Get the subfield (equivalent to extract).
date_sub(part, startdate, enddate)The number of complete partitions between the dates.
date_trunc(part, date)Truncate to specified precision .
datediff(part, startdate, enddate)The number of partition boundaries between the dates. Alias of date_diff.
datepart(part, date)Get the subfield (equivalent to extract). Alias of date_part.
datesub(part, startdate, enddate)The number of complete partitions between the dates. Alias of date_sub.
datetrunc(part, date)Truncate to specified precision . Alias of date_trunc.
dayname(date)The (English) name of the weekday.
extract(part from date)Get subfield from a date.
greatest(date, date)The later of two dates.
isfinite(date)Returns true if the date is finite, false otherwise.
isinf(date)Returns true if the date is infinite, false otherwise.
last_day(date)The last day of the corresponding month in the date.
least(date, date)The earlier of two dates.
make_date(year, month, day)The date for the given parts.
monthname(date)The (English) name of the month.
strftime(date, format)Converts a date to a string according to the format string .
time_bucket(bucket_width, date[, offset])Truncate date by the specified interval bucket_width. Buckets are offset by offset interval.
time_bucket(bucket_width, date[, origin])Truncate date by the specified interval bucket_width. Buckets are aligned relative to origin date. origin defaults to 2000-01-03 for buckets that don't include a month or year interval, and to 2000-01-01 for month and year buckets.
today()Current date (start of current transaction).
Description Current date (at start of current transaction).
Example current_date
Result 2022-10-08
Description Add the interval to the date.
Example date_add(DATE '1992-09-15', INTERVAL 2 MONTH)
Result 1992-11-15
Description The number of partition boundaries between the dates.
Example date_diff('month', DATE '1992-09-15', DATE '1992-11-14')
Result 2
Description Get the subfield (equivalent to extract).
Example date_part('year', DATE '1992-09-20')
Result 1992
Description The number of complete partitions between the dates.
Example date_sub('month', DATE '1992-09-15', DATE '1992-11-14')
Result 1
Description Truncate to specified precision .
Example date_trunc('month', DATE '1992-03-07')
Result 1992-03-01
Description The number of partition boundaries between the dates.
Example datediff('month', DATE '1992-09-15', DATE '1992-11-14')
Result 2
Alias date_diff.
Description Get the subfield (equivalent to extract).
Example datepart('year', DATE '1992-09-20')
Result 1992
Alias date_part.
Description The number of complete partitions between the dates.
Example datesub('month', DATE '1992-09-15', DATE '1992-11-14')
Result 1
Alias date_sub.
Description Truncate to specified precision .
Example datetrunc('month', DATE '1992-03-07')
Result 1992-03-01
Alias date_trunc.
Description The (English) name of the weekday.
Example dayname(DATE '1992-09-20')
Result Sunday
Description Get subfield from a date.
Example extract('year' FROM DATE '1992-09-20')
Result 1992
Description The later of two dates.
Example greatest(DATE '1992-09-20', DATE '1992-03-07')
Result 1992-09-20
Description Returns true if the date is finite, false otherwise.
Example isfinite(DATE '1992-03-07')
Result true
Description Returns true if the date is infinite, false otherwise.
Example isinf(DATE '-infinity')
Result true
Description The last day of the corresponding month in the date.
Example last_day(DATE '1992-09-20')
Result 1992-09-30
Description The earlier of two dates.
Example least(DATE '1992-09-20', DATE '1992-03-07')
Result 1992-03-07
Description The date for the given parts.
Example make_date(1992, 9, 20)
Result 1992-09-20
Description The (English) name of the month.
Example monthname(DATE '1992-09-20')
Result September
Description Converts a date to a string according to the format string .
Example strftime(date '1992-01-01', '%a, %-d %B %Y')
Result Wed, 1 January 1992
Description Truncate date by the specified interval bucket_width. Buckets are offset by offset interval.
Example time_bucket(INTERVAL '2 months', DATE '1992-04-20', INTERVAL '1 month')
Result 1992-04-01
Description Truncate date by the specified interval bucket_width. Buckets are aligned relative to origin date. origin defaults to 2000-01-03 for buckets that don't include a month or year interval, and to 2000-01-01 for month and year buckets.
Example time_bucket(INTERVAL '2 weeks', DATE '1992-04-20', DATE '1992-04-01')
Result 1992-04-15
Description Current date (start of current transaction).
Example today()
Result 2022-10-08
There are also dedicated extraction functions to get the subfields .
A few examples include extracting the day from a date, or the day of the week from a date.
Functions applied to infinite dates will either return the same infinite dates
(e.g, greatest) or NULL (e.g., date_part) depending on what "makes sense".
In general, if the function needs to examine the parts of the infinite date, the result will be NULL.
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