Each datepart and its abbreviations return the same value.
The return value depends on the language environment set by using SET LANGUAGE and by the default language of the login. If date is a string literal for some formats, the return value depends on the format specified by using SET DATEFORMAT. SET DATEFORMAT does not affect the return value when the date is a column expression of a date or time data type.
The following table lists all datepart arguments with corresponding return values for the statement SELECT DATEPART(datepart,'2007-10-30 12:15:32.1234567 +05:10'). The data type of the date argument is datetimeoffset(7). The nanosecond datepart return value has a scale of 9 (.123456700) and the last two positions are always 00.
| datepart |
Return value
|
| year, yyyy, yy | 2007 |
| quarter, qq, q | 4 |
| month, mm, m | 10 |
| dayofyear, dy, y | 303 |
| day, dd, d | 30 |
| week, wk, ww | 45 |
| weekday, dw | 1 |
| hour, hh | 12 |
| minute, n | 15 |
| second, ss, s | 32 |
| millisecond, ms | 123 |
| microsecond, mcs | 123456 |
| nanosecond, ns | 123456700 |
| TZoffset, tz | 310 |
week and weekday datepart Arguments
When datepart is week (wk, ww) or weekday (dw), the return value depends on the value that is set by using SET DATEFIRST.
January 1 of any year defines the starting number for the week datepart, for example: DATEPART (wk, 'Jan 1, xxxx') = 1, where xxxx is any year.
The following table lists the return value for week and weekday datepart for '2007-04-21 ' for each SET DATEFIRST argument. January 1 is a Sunday in the year 2007. April 21 is a Saturday in the year 2007. SET DATEFIRST 7, Sunday, is the default for U.S. English.
|
SET DATEFIRST
argument
|
week
returned
|
weekday
returned
|
| 1 | 16 | 6 |
| 2 | 17 | 5 |
| 3 | 17 | 4 |
| 4 | 17 | 3 |
| 5 | 17 | 2 |
| 6 | 17 | 1 |
| 7 | 16 | 7 |
year, month, and day datepart Arguments
The values that are returned for DATEPART (year, date), DATEPART (month, date), and DATEPART (day, date) are the same as those returned by the functions YEAR, MONTH, and DAY, f respectively.
ISO_WEEK datepart
ISO 8601 includes the ISO week-date system, a numbering system for weeks. Each week is associated with the year in which Thursday occurs. For example, week 1 of 2004 (2004W01) ran from Monday 29 December 2003 to Sunday, 4 January 2004. The highest week number in a year might be 52 or 53. This style of numbering is typically used in European countries, but rare elsewhere.
The numbering system in different countries might not comply with the ISO standard. There are at least six possibilities as shown in the following table
|
First day of week
|
First week of year contains
|
Weeks assigned two times
|
Used by/in
|
| Sunday | 1 January, First Saturday, 1–7 days of year | Yes | United States |
| Monday | 1 January, First Sunday, 1–7 days of year | Yes | Most of Europe and the United Kingdom |
| Monday | 4 January, First Thursday, 4–7 days of year | No | ISO 8601, Norway, and Sweden |
| Monday | 7 January, First Monday, 7 days of year | No | |
| Wednesday | 1 January, First Tuesday, 1–7 days of year | Yes | |
| Saturday | 1 January, First Friday, 1–7 days of year | Yes | |
TZoffset
The TZoffset (tz) is returned as the number of minutes (signed). The following statement returns a time zone offset of 310 minutes.
|
SELECT DATEPART (TZoffset, 2007-05-10 00:00:01.1234567 +05:10); |
If the datepart argument is TZoffset (tz) and the date argument is not of datetimeoffset data type, NULL is returned.
smalldatetime date Argument
Default Returned for a datepart That Is Not in a date Argument
If the data type of the date argument does not have the specified datepart, the default for that datepart will be returned.
For example, the default year-month-day for any date data type is 1900-01-01. The following statement has date part arguments for datepart, a time argument for date, and returns 1900, 1, 1, 1, 2.
|
SELECT DATEPART(year, '12:10:30.123')
,DATEPART(month, '12:10:30.123')
,DATEPART(day, '12:10:30.123')
,DATEPART(dayofyear, '12:10:30.123')
,DATEPART(weekday, '12:10:30.123'); |
The default hour-minute-second for the time data type is 00:00:00. The following statement has time part arguments for datepart, a date argument for date, and returns 0, 0, 0.
|
SELECT DATEPART(hour, '2007-06-01')
,DATEPART(minute, '2007-06-01')
,DATEPART(second, '2007-06-01'); |
Fractional Seconds
Fractional seconds are returned as shown in the following statements:
|
SELECT DATEPART(millisecond, '00:00:01.1234567'); -- Returns 123
SELECT DATEPART(microsecond, '00:00:01.1234567'); -- Returns 123456
SELECT DATEPART(nanosecond, '00:00:01.1234567'); -- Returns 123456700 |