FUNCTION:
DateDiff( )
DateDiff(Interval, Date1, Date2, FirstDayofWeek, FirstWeekofYear)
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.
Code:
<%=DateDiff("d", Date, "1/1/2000") %>
Output:
291
The order of the two dates determines if the difference is represented as a positive or negative value.
Code:
<% olddate = #6/26/43# %>
<% nowdate = Now %>
<% =DateDiff("s", nowdate, olddate) %>
Output:
-3130748108
There are two optional arguments.
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.
Code:
<% =DateDiff("w", Date, "1/1/2001", 3) %>
Output:
93
Code:
<% =DateDiff("w", Date, "1/1/2001", VBTUESDay) %>
Output:
93
FirstWeekofYear
The FirstWeekofYea argument must only use the constants or values defined in the Date And Time CONSTANTS which are listed above.
Code:
<% =DateDiff("ww", Date, "1/1/2001", 1, VBFIRSTFOURDayS)%>
Output:
94