date (Transact-SQL)

مقالة
08/28/2013

Defines a date.

date Description

Property	Value
Syntax	date
Usage	DECLARE @MyDate date CREATE TABLE Table1 ( Column1 date )
Default string literal format (used for down-level client)	YYYY-MM-DD For more information, see the "Backward Compatibility for Down-level Clients" section that follows.
Range	0001-01-01 through 9999-12-31 January 1, 1 A.D. through December 31, 9999 A.D.
Element ranges	YYYY is four digits from 0001 to 9999 that represent a year. MM is two digits from 01 to 12 that represent a month in the specified year. DD is two digits from 01 to 31, depending on the month, that represent a day of the specified month.
Character length	10 positions
Precision, scale	10, 0
Storage size	3 bytes, fixed
Storage structure	1, 3-byte integer stores date.
Accuracy	One day
Default value	1900-01-01 This value is used for the appended date part for implicit conversion from time to datetime2 or datetimeoffset.
Calendar	Gregorian
User-defined fractional second precision	No
Time zone offset aware and preservation	No
Daylight saving aware	No

Supported String Literal Formats for date

The following tables show the valid string literal formats for the date data type.

Numeric	Description
mdy [m]m/dd/[yy]yy [m]m-dd-[yy]yy [m]m.dd.[yy]yy myd mm/[yy]yy/dd mm-[yy]yy/dd [m]m.[yy]yy.dd dmy dd/[m]m/[yy]yy dd-[m]m-[yy]yy dd.[m]m.[yy]yy dym dd/[yy]yy/[m]m dd-[yy]yy-[m]m dd.[yy]yy.[m]m ymd [yy]yy/[m]m/dd [yy]yy-[m]m-dd [yy]yy-[m]m-dd	[m]m, dd, and [yy]yy represents month, day, and year in a string with slash marks (/), hyphens (-), or periods (.) as separators. Only four- or two-digit years are supported. Use four-digit years whenever possible. To specify an integer from 0001 to 9999 that represents the cutoff year for interpreting two-digit years as four-digit years, use the Configure the two digit year cutoff Server Configuration Option. A two-digit year that is less than or equal to the last two digits of the cutoff year is in the same century as the cutoff year. A two-digit year that is greater than the last two digits of the cutoff year is in the century that comes before the cutoff year. For example, if the two-digit year cutoff is the default 2049, the two-digit year 49 is interpreted as 2049 and the two-digit year 50 is interpreted as 1950. The default date format is determined by the current language setting. You can change the date format by using the SET LANGUAGE and SET DATEFORMAT statements. The ydm format is not supported for date.

mdy

[m]m/dd/[yy]yy

[m]m-dd-[yy]yy

[m]m.dd.[yy]yy

myd

mm/[yy]yy/dd

mm-[yy]yy/dd

[m]m.[yy]yy.dd

dmy

dd/[m]m/[yy]yy

dd-[m]m-[yy]yy

dd.[m]m.[yy]yy

dym

dd/[yy]yy/[m]m

dd-[yy]yy-[m]m

dd.[yy]yy.[m]m

ymd

[yy]yy/[m]m/dd

[yy]yy-[m]m-dd

[m]m, dd, and [yy]yy represents month, day, and year in a string with slash marks (/), hyphens (-), or periods (.) as separators.

Only four- or two-digit years are supported. Use four-digit years whenever possible. To specify an integer from 0001 to 9999 that represents the cutoff year for interpreting two-digit years as four-digit years, use the Configure the two digit year cutoff Server Configuration Option.

A two-digit year that is less than or equal to the last two digits of the cutoff year is in the same century as the cutoff year. A two-digit year that is greater than the last two digits of the cutoff year is in the century that comes before the cutoff year. For example, if the two-digit year cutoff is the default 2049, the two-digit year 49 is interpreted as 2049 and the two-digit year 50 is interpreted as 1950.

The default date format is determined by the current language setting. You can change the date format by using the SET LANGUAGE and SET DATEFORMAT statements.

The ydm format is not supported for date.

Alphabetical	Description
mon [dd][,] yyyy mon dd[,] [yy]yy mon yyyy [dd] [dd] mon[,] yyyy dd mon[,][yy]yy dd [yy]yy mon [dd] yyyy mon yyyy mon [dd] yyyy [dd] mon	mon represents the full month name or the month abbreviation given in the current language. Commas are optional and capitalization is ignored. To avoid ambiguity, use four-digit years. If the day is missing, the first day of the month is supplied.

mon [dd][,] yyyy

mon dd[,] [yy]yy

mon yyyy [dd]

[dd] mon[,] yyyy

dd mon[,][yy]yy

dd [yy]yy mon

[dd] yyyy mon

yyyy mon [dd]

yyyy [dd] mon

mon represents the full month name or the month abbreviation given in the current language. Commas are optional and capitalization is ignored.

To avoid ambiguity, use four-digit years.

If the day is missing, the first day of the month is supplied.

ISO 8601	Descripton
YYYY-MM-DD YYYYMMDD	Same as the SQL standard. This is the only format that is defined as an international standard.

YYYY-MM-DD

YYYYMMDD

Same as the SQL standard. This is the only format that is defined as an international standard.

Unseparated	Description
[yy]yymmdd yyyy[mm][dd]	The date data can be specified with four, six, or eight digits. A six- or eight-digit string is always interpreted as ymd. The month and day must always be two digits. A four-digit string is interpreted as year.

[yy]yymmdd

yyyy[mm][dd]

The date data can be specified with four, six, or eight digits. A six- or eight-digit string is always interpreted as ymd. The month and day must always be two digits. A four-digit string is interpreted as year.

ODBC	Description
{ d 'yyyy-mm-dd' }	ODBC API specific. Functions in SQL Server 2012 as in SQL Server 2005.

{ d 'yyyy-mm-dd' }

ODBC API specific.

Functions in SQL Server 2012 as in SQL Server 2005.

W3C XML format	Description
yyyy-mm-ddTZD	Specifically supported for XML/SOAP usage. TZD is the time zone designator (Z or +hh:mm or -hh:mm): hh:mm represents the time zone offset. hh is two digits, ranging from 0 to 14, that represent the number of hours in the time zone offset. MM is two digits, ranging from 0 to 59, that represent the number of additional minutes in the time zone offset. + (plus) or – (minus) the mandatory sign of the time zone offset. This indicates that the time zone offset is added or subtracted from the Coordinated Universal Times (UTC) time to obtain the local time. The valid range of time zone offset is from -14:00 to +14:00.

yyyy-mm-ddTZD

Specifically supported for XML/SOAP usage.

TZD is the time zone designator (Z or +hh:mm or -hh:mm):

hh:mm represents the time zone offset. hh is two digits, ranging from 0 to 14, that represent the number of hours in the time zone offset.
MM is two digits, ranging from 0 to 59, that represent the number of additional minutes in the time zone offset.
+ (plus) or – (minus) the mandatory sign of the time zone offset. This indicates that the time zone offset is added or subtracted from the Coordinated Universal Times (UTC) time to obtain the local time. The valid range of time zone offset is from -14:00 to +14:00.

ANSI and ISO 8601 Compliance

date complies with the ANSI SQL standard definition for the Gregorian calendar: "NOTE 85 - Datetime data types will allow dates in the Gregorian format to be stored in the date range 0001–01–01 CE through 9999–12–31 CE."

The default string literal format, which is used for down-level clients, complies with the SQL standard form which is defined as YYYY-MM-DD. This format is the same as the ISO 8601 definition for DATE.

Backward Compatibility for Down-level Clients

Some down-level clients do not support the time, date, datetime2 and datetimeoffset data types. The following table shows the type mapping between an up-level instance of SQL Server and down-level clients.

SQL Server 2012 data type	Default string literal format passed to down-level client	Down-level ODBC	Down-level OLEDB	Down-level JDBC	Down-level SQLCLIENT
time	hh:mm:ss[.nnnnnnn]	SQL_WVARCHAR or SQL_VARCHAR	DBTYPE_WSTRor DBTYPE_STR	Java.sql.String	String or SqString
date	YYYY-MM-DD	SQL_WVARCHAR or SQL_VARCHAR	DBTYPE_WSTRor DBTYPE_STR	Java.sql.String	String or SqString
datetime2	YYYY-MM-DD hh:mm:ss[.nnnnnnn]	SQL_WVARCHAR or SQL_VARCHAR	DBTYPE_WSTRor DBTYPE_STR	Java.sql.String	String or SqString
datetimeoffset	YYYY-MM-DD hh:mm:ss[.nnnnnnn] [+\|-]hh:mm	SQL_WVARCHAR or SQL_VARCHAR	DBTYPE_WSTRor DBTYPE_STR	Java.sql.String	String or SqString

Converting Date and Time Data

When you convert to date and time data types, SQL Server rejects all values it cannot recognize as dates or times. For information about using the CAST and CONVERT functions with date and time data, see CAST and CONVERT (Transact-SQL).

Converting date to Other Date and Time Types

The following table describes what occurs when a date data type is converted to other date and time data types.

Data type to convert to	Conversion details
time(n)	The conversion fails, and error message 206 is raised: "Operand type clash: date is incompatible with time".
datetime	The date is copied and the time component is set to 00:00:00.000. The following code shows the results of converting a date value to a datetime value. `DECLARE @date date= '12-10-25'; DECLARE @datetime datetime= @date; SELECT @date AS '@date', @datetime AS '@datetime'; --Result --@date @datetime ------------ ----------------------- --2025-12-10 2025-12-10 00:00:00.000 -- --(1 row(s) affected)`
smalldatetime	When the date value is in the range of a smalldatetime, the date component is copied and the time component is set to 00:00:00. When the date value is outside the range of a smalldatetime value, error message 242 is raised: "The conversion of a date data type to a smalldatetime data type results in an out-of-range value;and the smalldatetime value is set to NULL. The following code shows the results of converting a date value to a smalldatetime value. `DECLARE @date date= '1912-10-25'; DECLARE @smalldatetime smalldatetime = @date; SELECT @date AS '@date', @smalldatetime AS '@smalldatetime'; --Result --@date @smalldatetime ------------ ----------------------- --1912-10-25 1912-10-25 00:00:00 -- --(1 row(s) affected)`
datetimeoffset(n)	The date is copied, and the time is set to 00:00.0000000 +00:00. The following code shows the results of converting a date value to a datetimeoffset(3) value. `DECLARE @date date = '1912-10-25'; DECLARE @datetimeoffset datetimeoffset(3) = @date; SELECT @date AS '@date', @datetimeoffset AS '@datetimeoffset'; --Result --@date @datetimeoffset ------------ ------------------------------ --1912-10-25 1912-10-25 00:00:00.000 +00:00 -- --(1 row(s) affected)`
datetime2(n)	The date component is copied, and the time component is set to 00:00:00.00 regardless of the value of (n). The following code shows the results of converting a date value to a datetime2(3) value. `DECLARE @date date = '1912-10-25'; DECLARE @datetime2 datetime2(3) = @date; SELECT @date AS '@date', @datetime2 AS '@datetime2(3)'; --Result --@date @datetime2(3) ------------ ----------------------- --1912-10-25 1912-10-25 00:00:00.00 -- --(1 row(s) affected)`

Converting String Literals to date

Conversions from string literals to date and time types are permitted if all parts of the strings are in valid formats. Otherwise, a runtime error is raised. Implicit conversions or explicit conversions that do not specify a style, from date and time types to string literals will be in the default format of the current session. The following table shows the rules for converting a string literal to the date data type.

Input string literal	date
ODBC DATE	ODBC string literals are mapped to the datetime data type. Any assignment operation from ODBC DATETIME literals into a date type will cause an implicit conversion between datetime and this type as defined by the conversion rules.
ODBC TIME	See previous ODBC DATE rule.
ODBC DATETIME	See previous ODBC DATE rule.
DATE only	Trivial
TIME only	Default values are supplied.
TIMEZONE only	Default values are supplied.
DATE + TIME	The DATE part of the input string is used.
DATE + TIMEZONE	Not allowed.
TIME + TIMEZONE	Default values are supplied.
DATE + TIME + TIMEZONE	The DATE part of local DATETIME will be used.

Examples

The following example compares the results of casting a string to each date and time data type.

SELECT 
     CAST('2007-05-08 12:35:29. 1234567 +12:15' AS time(7)) AS 'time' 
    ,CAST('2007-05-08 12:35:29. 1234567 +12:15' AS date) AS 'date' 
    ,CAST('2007-05-08 12:35:29.123' AS smalldatetime) AS 
        'smalldatetime' 
    ,CAST('2007-05-08 12:35:29.123' AS datetime) AS 'datetime' 
    ,CAST('2007-05-08 12:35:29. 1234567 +12:15' AS datetime2(7)) AS 
        'datetime2'
    ,CAST('2007-05-08 12:35:29.1234567 +12:15' AS datetimeoffset(7)) AS 
        'datetimeoffset';

Here is the result set.

Data type	Output
time	12:35:29. 1234567
date	2007-05-08
smalldatetime	2007-05-08 12:35:00
datetime	2007-05-08 12:35:29.123
datetime2	2007-05-08 12:35:29. 1234567
datetimeoffset	2007-05-08 12:35:29.1234567 +12:15

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