You can use the DateDiff function to determine how many time intervals exist between two dates. For example, you can use DateDiff to calculate the number of days between an order date and its shipdate or the number of weeks between today and the end of the year.
interval is the interval of time to use to calculate the difference between date1 and date2. The following is a list of valid interval values.
Interval
Description
yyyy
Year
q
Quarter
m
Month
y
Day of year
w
Weekday
ww
Week
h
Hour
n
Minute
s
Second
date1, date 2 are the two dates to calculate you want to use in the calculation.
firstdayofweek is optional argument that specifies the first day of the week. If not specified, Sunday is assumed. If not specified, the first week is assumed to be the week in which Jan 1 occurs. The following is a list of valid parameters for firstweekofyear.
Constant
Value
Description
vbUseSystem
0
Use the NLS API settings
vbSunday
1
Sunday (default used)
vbMonday
2
Monday
vbTuesday
3
Tuesday
vbWednesday
4
Wednesday
vbThursday
5
Thursday
vbFriday
6
Friday
vbSaturday
7
Saturday
firstweekofyear is optional argument that specifies the first week of the year. The following is a list of valid parameters for firstweekday.
Constant
Value
Description
vbUseSystem
0
Use the NLS API settings
vbFirstJan1
1
Start with the first week in which January 1 occurs (default).
vbFirstFourDays
2
Start with the first week in the year that has at least 4 days
Dim MyNumber As Integer MyNumber = DateDiff('d',#10/06/1998#,#12/09/1998#)
This example uses the DateDiff function to display the number of days between a given date and today. Now the MyNumber variable would contain the value of 64.
SQL query
You can also use the DateDiff function in a query.
SELECT DateDiff('d',#05/05/1985#, Now()) AS Expr1 FROM Orders