DateDiff

The DateDiff function returns the number of intervals between two dates.

Syntax :

DateDiff(interval,date1,date2[,firstdayofweek[,firstweekofyear]])

Parameters	Description
interval	Required. The interval you want to use to calculate the differences between date1 and date2. Can take the following values : yyyy - Year q - Quarter m - Month y - Day of year d - Day w - Weekday ww - Week of year h - Hour n - Minute s - Second
date1,date2	Required. Date expressions. Two dates you want to use in the calculation.
firstdayofweek	Optional. Specifies the day of the week. Can take the following values : 0 - vbUseSystemDayOfWeek - Use National Language Support API setting 1 - vbSunday - Sunday(default) 2 - vbMonday - Monday 3 - vbTuesday - Tuesday 4 - vbWednesday - Wednesday 5 - vbThursday - Thursday 6 - vbFriday - Friday 7 - vbSaturday - Saturday
firstweekofyear	Optional. Specifies the first week of the year. Can take the following values : 0 - vbUseSystem - Use National Language Support (NLS) API Setting. 1 - vbFirstjan1 - Start with the week in which January 1 occurs (default). 2 - vbFirstFourDays - With this we Start with the week that has at least four days in the new year 3 - vbFirstFullWeek - Start with the first full week of the new year.

Examples :

Example 1

To get the difference between January 31 2009, and January 31 2010 :

fromDate="31-Jan-09 00:00:00"
toDate="31-Jan-10 23:59:00"

dDateDiff = (DateDiff("yyyy",fromDate,toDate) & " ")
dDateDiff = (DateDiff("q",fromDate,toDate) & " ")
dDateDiff = (DateDiff("m",fromDate,toDate) & " ")
dDateDiff = (DateDiff("y",fromDate,toDate) & " ")
dDateDiff = (DateDiff("d",fromDate,toDate) & " ")
dDateDiff = (DateDiff("w",fromDate,toDate) & " ")
dDateDiff = (DateDiff("ww",fromDate,toDate) & " ")
dDateDiff = (DateDiff("h",fromDate,toDate) & " ")
dDateDiff = (DateDiff("n",fromDate,toDate) & " ")
dDateDiff = (DateDiff("s",fromDate,toDate) & " ")
DEBUG(dDateDiff)

Result :

dDateDiff
= 1
= 4
= 12
= 365
= 365
= 52
= 53
= 8783
= 527039
= 31622340

Example 2 :

How many weeks (start on Monday), between December 31 2009 and December 31 2012 :

fromDate = CDate("2009/12/31")
toDate=CDate("2012/12/31")

dDateDiff = (DateDiff("w",fromDate,toDate,vbMonday))
DEBUG(dDateDiff)

Result :

dDateDiff
= 156