DateDiff Function
Returns the number of intervals between two dates.
DateDiff(interval, date1, date2
[,firstdayofweek[, firstweekofyear]])
The DateDiff function syntax has these parts:
Arguments
interval
Required. String expression that is the interval you want to use to calculate the differences
between date1 and date2. See Settings section for values.
date1, date2
Required. Date expressions. Two dates you want to use in the
calculation.
firstdayofweek
Optional. Constant that specifies the day of the week. If not
specified, Sunday is assumed. See Settings section for values.
firstweekofyear
Optional. Constant that specifies the first week of the year. If
not specified, the first week is assumed to be the week in which January 1
occurs. See Settings section for values.
Settings
The interval argument can have the following values:
| 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 |
The firstdayofweek argument can have the following values:
| Constant | Value | Description | | vbUseSystem | 0 | Use National Language Support (NLS) API setting. | | vbSunday | 1 | Sunday (default) | | vbMonday | 2 | Monday | | vbTuesday | 3 | Tuesday | | vbWednesday | 4 | Wednesday | | vbThursday | 5 | Thursday | | vbFriday | 6 | Friday | | vbSaturday | 7 | Saturday |
The firstweekofyear argument can have the following values:
| Constant | Value | Description | | vbUseSystem | 0 | Use National Language Support (NLS) API setting. | | vbFirstJan1 | 1 | Start with the week in which January 1 occurs (default). | | vbFirstFourDays | 2 | Start with the week that has at least four days in the new year. | | vbFirstFullWeek | 3 | Start with the first full weekof the new year. |
Remarks
You can use the DateDiff function to determine how many specified time
intervals exist between two dates. For example, you might use DateDiff to
calculate the number of days between two dates, or the number of weeks between
today and the end of the year.
To calculate the number of days between date1 and date2, you
can use either Day of year ("y") or Day ("d"). When interval is Weekday
("w"), DateDiff returns the number of weeks between the two dates. If
date1 falls on a Monday, DateDiff counts the number of Mondays
until date2. It counts date2 but not date1. If
interval is Week ("ww"), however, the DateDiff function returns
the number of calendar weeks between the two dates. It counts the number of
Sundays between date1 and date2. DateDiff counts
date2 if it falls on a Sunday; but it doesn't count date1, even if
it does fall on a Sunday.
If date1 refers to a later point in time than date2, the
DateDiff function returns a negative number.
The firstdayofweek argument affects calculations that use the "w" and
"ww" interval symbols.
If date1 or date2 is a date literal, the specified year becomes
a permanent part of that date. However, if date1 or date2 is
enclosed in quotation marks (" ") and you omit the year, the current year is
inserted in your code each time the date1 or date2 expression is
evaluated. This makes it possible to write code that can be used in different
years.
When comparing December 31 to January 1 of the immediately succeeding year,
DateDiff for Year ("yyyy") returns 1 even though only a day has
elapsed.
The following example uses the DateDiff function to display the number
of days between a given date and today: Function DiffADate(theDate)
DiffADate = "Days from today: " & DateDiff("d", Now, theDate)
End Function
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