DateDiff

Description

Determines the integer number of units by which date1 is less than date2.

Returns

A number of units, of type datepart.

Category

Date and time functions

Function syntax

DateDiff(datepart, date1, date2)

See also

DateAddDatePartCreateTimeSpan

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.

  • yyyy : Years
  • q: Quarters
  • m: Months
  • y: Days of year (same as d)
  • d: Days
  • w: Weekdays
  • ww : Weeks
  • h: Hours
  • n: Minutes
  • s: Seconds

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.

Note:

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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