DATEDIFF (T-SQL)

Returns the number of date and time boundaries crossed between two specified dates.

Syntax

DATEDIFF(datepart, startdate, enddate)

Arguments

datepart

Is the parameter that specifies on which part of the date to calculate the difference. The table lists dateparts and abbreviations recognized by Microsoft® SQL Server™.

Datepart	Abbreviations
year	yy, yyyy
quarter	qq, q
month	mm, m
dayofyear	dy, y
day	dd, d
week	wk, ww
hour	hh
minute	mi, n
second	ss, s
millisecond	ms

startdate

Is the beginning date for the calculation. startdate is an expression that returns a datetime or smalldatetime value, or a character string in a date format.

Because smalldatetime is accurate only to the minute, when a smalldatetime value is used, seconds and milliseconds are always 0.

If you specify only the last two digits of the year, values that are less than or equal to the last two digits of the value of the two digit year cutoff configuration option are in the same century as the cutoff year. Values that are greater than the last two digits of the value of this option are in the century that precedes the cutoff year. For example, if two digit year cutoff is 2049 (default), 49 is interpreted as 2049 and 2050 is interpreted as 1950. To avoid ambiguity, use four-digit years.

For information about specifying time values, see Time Formats. For information about specifying dates, see datetime and smalldatetime.

enddate

Is the ending date for the calculation. enddate is an expression that returns a datetime or smalldatetime value, or a character string in a date format.

Return Types

integer

Remarks

startdate is subtracted from enddate. If startdate is later than enddate, a negative value is returned.

DATEDIFF produces an error if the result is out of range for integer values. For milliseconds, the maximum number that can be represented is 24 days, 20 hours, 31 minutes and 23.647 seconds. For seconds, the maximum number that can be represented is approximately 68 years.

The method of counting crossed boundaries such as minutes, seconds, and milliseconds makes the result given by DATEDIFF consistent across all data types. The result is a signed integer value equal to the number of datepart boundaries crossed between the first and second date. For example, the number of weeks between Sunday, January 4 and Sunday, January 11, is 1.

Examples

This example determines the difference in days between the current date and the publication date for titles in the pubs database.

USE pubs

GO

SELECT DATEDIFF(day, pubdate, getdate()) AS no_of_days

FROM titles