InterSystems SQL Reference
DATENAME
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A date/time function that returns a string representing the value of the specified part of a date/time expression.
Synopsis
DATENAME(datepart,date-expression)
The
DATENAME function returns the name of the specified part (such as the month "June") of a date/time value. The result is returned as data type VARCHAR(20). If the result is numeric (such as "23" for the day), it is still returned as a VARCHAR(20) string. To return this information as an integer, use
DATEPART. To return a string containing multiple date parts, use
TO_DATE.
Note that
DATENAME is provided for Sybase and Microsoft SQL Server compatibility.
This function can also be invoked from ObjectScript using the
DATENAME() method call:
The
datepart argument can be a string containing one (and only one) of the following date/time components, either the full name (the Date Part column) or its abbreviation (the Abbreviation column). These
datepart component names and abbreviations are not case-sensitive.
If you specify an invalid
datepart value as a literal, an SQLCODE -8 error code is issued. However, if you supply an invalid
datepart value as a host variable, no SQLCODE error is issued and the
DATENAME function returns a value of NULL.
The preceding table shows the default return values for the various date parts. You can modify the returned values for several of these date parts by using the
SET OPTION command with various time and date options.
week: InterSystems IRIS can be configured to determine the week of the year for a given date using either the InterSystems IRIS default algorithm or the ISO 8601 standard algorithm. For further details, refer to the
WEEK function.
weekday: The InterSystems IRIS default for weekday is to designate Sunday as first day of the week (weekday=1). However, you can configure the first day of the week to another value, or you can apply the ISO 8601 standard which designates Monday as first day of the week. For further details, refer to the
DAYOFWEEK function.
millisecond: InterSystems IRIS returns a string containing the number of milliseconds (thousandths of a second). If the
date-expression has more than three fractional digits of precision, InterSystems IRIS truncates it to three digits and returns this number as a string.
A
datepart can be specified as a quoted string or without quotes. These syntax variants perform slightly different operations:
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An InterSystems IRIS %Date logical value (+$H)
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An InterSystems IRIS %String (or compatible) value
The InterSystems IRIS %String (or compatible) value can be in any of the following formats:
mmdelimiterdddelimiter[yy]yy
dd Mmm[mm][,][yy]yy
dd [yy]yy Mmm[mm]
yyyy Mmm[mm] dd
yyyy [dd] Mmm[mm]
where
delimiter is a slash (/), hyphen (-), or period (.).
If the year is given as two digits, InterSystems IRIS checks the sliding window to interpret the date. The system default for the sliding window can be set via the %DATE utility, which is documented only in the legacy documentation available at
http://docs.intersystems.com/priordocexcerpts. For information on setting the sliding window for the current process, see the documentation for the ObjectScript
$ZDATE,
$ZDATEH,
$ZDATETIME and
$ZDATETIMEH functions.
HH:MM[:SS:SSS][{AM|PM}]
HH:MM[:SS.S]
HH['']{AM|PM}
If the
date-expression specifies a time format but does not specify a date format,
DATENAME defaults to the date 1900–01–01, which has a weekday value of Monday.
DATENAME performs the following checks on input values. If a value fails a check, the null string is returned.
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A valid
date-expression may consist of a date string (yyyy-mm-dd), a time string (hh:mm:ss), or a date and time string (yyyy-mm-dd hh:mm:ss). If both date and time are specified, both must be valid. For example, you can return a Year value if no time string is specified, but you cannot return a Year value if an invalid time string is specified.
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A date string must be complete and properly formatted with the appropriate number of elements and digits for each element, and the appropriate separator character. For example, you cannot return a Year value if the Day value is omitted. Years must be specified as four digits.
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A time string must be properly formatted with the appropriate separator character. Because a time value can be zero, you can omit one or more time elements (either retaining or omitting the separator characters) and these elements will be returned with a value of zero. Thus, 'hh:mm:ss', 'hh:mm:', 'hh:mm', 'hh::ss', 'hh::', 'hh', and ':::' are all valid. To omit the Hour element,
date-expression must not have a date portion of the string, and you must retain at least one separator character (:).
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Date and time values must be within a valid range. Years: 1841 through 9999. Months: 1 through 12. Days: 1 through 31. Hours: 0 through 23. Minutes: 0 through 59. Seconds: 0 through 59.
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The number of days in a month must match the month and year. For example, the date '02–29' is only valid if the specified year is a leap year.
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Most date and time values less than 10 may include or omit a leading zero. However, an Hour value of less than 10 must include the leading zero if it is part of a datetime string. Other non-canonical integer values are not permitted. Therefore, a Day value of '07' or '7' is valid, but '007', '7.0' or '7a' are not valid.
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If
date-expression specifies a time format but does not specify a date format,
DATENAME does not perform range validation for the time component values.
In the following example, each
DATENAME returns 'Wednesday' because that is the day of week ('dw') of the specified date:
SELECT DATENAME('dw','2018-02-21') AS DayName,
DATENAME(dw,'02/21/2018') AS DayName,
DATENAME('DW',64700) AS DayName
The following example returns 'December' because that is the month name ('mm') of the specified date:
SELECT DATENAME('mm','2018-12-20 12:00:00') AS MonthName
The following example returns '2018' (as a string) because that is the year ('yy') of the specified date:
SELECT DATENAME('yy','2018-12-20 12:00:00') AS Year
Note that the above examples use the abbreviations of the date parts. However, you can specify the full name, as in this example:
SELECT DATENAME('year','2018-12-20 12:00:00') AS Year
The following example returns the current quarter, week-of-year, and day-of-year. Each value is returned as a string:
SELECT DATENAME('Q',$HOROLOG) AS Q,
DATENAME('WK',$HOROLOG) AS WkCnt,
DATENAME('DY',$HOROLOG) AS DayCnt
SET a="year"
SET b=$HOROLOG
&sql(SELECT DATENAME(:a,:b) INTO :c)
WRITE "this year is: ",c
The following example uses a subquery to returns records from Sample.Person whose day of birth was a Wednesday:
SELECT Name AS WednesdaysChild,DOB
FROM (SELECT Name,DOB,DATENAME('dw',DOB) AS Wkday FROM Sample.Person)
WHERE Wkday='Wednesday'
ORDER BY DOB