The DateDiff function calculates the amount of time between two different dates. There are three mandatory arguments:
Interval: The Interval argument defines the the type of time interval you wish to use to calculate the time difference. Only the following settings can be used. You must place the setting inside a pair of double quotes.
SETTING' DESCRIPTION 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: The Date1 argument is the first date.
Date2: The Date2 argument is the second date.
<%=DateDiff("d", Date, "1/1/2000") %>
The order of the two dates determines if the difference is represented as a positive or negative value.
FirstDayofWeek: The FirstDayofWeek argument must only use the constants or values defined below in the Date And Time CONSTANTS.
CONSTANT VALUE DESCRIPTION
VBSunday 1 Sunday
VBMonday 2 Monday
VBTuesday 3 Tuesday
VBWednesday 4 Wednesday
VBThursday 5 Thursday
VBFriday 6 Friday
VBSaturday 7 Saturday
VBFirstJan1 1 Week of January 1
VBFirstFourDays 2 First week of the year that has at least four days
VBFirstFullWeek 3 First full week of the year
VBUseSystem 0 Use the date format of the computer's regionsl settings
VBUseSystemDayOfWeek 0 Use the first full day of the week as defined by the system settings
In this example, Tuesday is defined to be the first day of the week. The output is how many weeks, which are now defined to start on Tuesday, are left between the current date and 1/1/2001.
<% =DateDiff("w", Date, "1/1/2001", 3) %>
<% =DateDiff("w", Date, "1/1/2001", VBTUESDAY) %>
FirstWeekofYear: The FirstWeekofYear argument must only use the constants or values defined in the Date And Time CONSTANTS which are listed above.