DateDiff and SQL sort

Firstly i want to use DateDiff to establish the amount of time between a Login and Logout time? Can this be done? and what values can DateDiff return?

Also, how can i sort by Date using if i'm using an SQL statement? When i try to do this only the first segment of the date is sorted, but everything after the first slash isn't sorted. How can i sort using the whole date?

thanks

DateDiff(interval,Date1,Date2[,FirstDayofWeek[,FirstWeekOfYear]

Interval can be:
yyyy Year
q Quarter
m Month
y Day of Year
d Day
w Weekday
ww Week
h Hour
m Minute
s Second

FirstDayofWeek 0 - System Date
1 - Sunday
7 - Saturday

FirstWeekofYear 0 - System
1 Week when Jan 1 occurs
2 Has at least 4 days in it
3 First Full Week of year

Put the Interval in Quotes.

VB Code:

DateDiff("d",now,"2/20/05")  = 1

Second question:

VB Code:

"SELECT * FROM tablename ORDER BY field2 DESC"

The sorting issue may be from the field being a data type other then a Date/Time format.
So when you have, say a text field storing string date values, it will sort based on text
values and not date values.

If you need to retain a text field data type then you can format the field in whatever control
you presenting it in with a preceeding zero for single digit months and also for the days and
years, depending on how you want the format to be.

1/1/01 <-> 01/01/2005 This will sort correctly in either data or text formats.

Can DateDiff only return whole numbers?

i did

Code:

---

MsgBox DateDiff("h", "13:00:00", "16:30:00")

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and it returned 3 instead of 3:30

p.s. the data type of Date is Date/Time and i know how to construct the SQL statement, but it doesn't work as explained earlier

You could use Minutes instead

I then get a return of 0