Description
Determines the integer number of units by which date1 is less than date2.
Returns
A number of units, of type datepart.
Category
Function syntax
DateDiff(datepart, date1, date2)
See also
DateAdd, DatePart, CreateTimeSpan
History
ColdFusion MX:
- Changed how negative date differences are calculated: this function calculates negative date differences correctly; its output may be different from that in earlier releases.
Parameters
Parameter |
Description |
|---|---|
datepart |
String that specifies the units in which to count; for example yyyy requests a date difference in whole years.
Note: The mask w as weekdays is only valid for the 2018 release of ColdFusion. For 2016 and earlier versions of ColdFusion, w returns the number of weeks. |
date1 |
Date/time object, in the range 100 AD-9999 AD. |
date2 |
Date/time object, in the range 100 AD-9999 AD. |
Usage
The DateDiff function determines the number of complete datepart units between the two dates; for example, if the datepart parameter is "m" and the dates differ by 55 days, the function returns 1 .Enclose string constant dates in quotation marks. If the text contains only numbers (such 1932 ), and is not surrounded by quotation marks, ColdFusion interprets it as a date/time object, resulting in an incorrect value.
In the DateDiff function, there is a difference in how the date difference is calculated for the member function. For example, in the code below,
<cfscript>
date1="2018-09-25"
date2="2018-10-25"
diffA=dateDiff("ww", date1, date2)
writeOutput(diffA) // 4
diffB=date1.diff("ww",date2)
writeOutput(diffB) // -4
</cfscript>
The first writeOutput produces a difference of 4 weeks, whereas the second writeOutput produces a difference of -4 weeks. Using DateDiff, the difference is calculated as date2-date1, whereas using the member function, the difference is calculated as date1-date2.
It is a known behavior in ColdFusion and the results are as expected.
Example
<cfscript>
Date1 = "{ts '2018-11-15 12:13:50'}";
Date2 = "{ts '2018-12-15 12:13:50'}";
diff= DateDiff("d",Date1,Date2)
diff1= DateDiff("ww",Date1,Date2)
diff2= DateDiff("m",Date1,Date2)
writeOutput("difference in date is : " & diff & " days or" & "<br/>" )
writeOutput("difference in date is : " & diff1 & " weeks or" & "<br/>")
writeOutput("difference in date is : " & diff2 & " month" & "<br/>")
</cfscript>
Output
difference in date is : 30 days or
difference in date is : 4 weeks or
difference in date is : 1 month
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