Hi guys
I'd like to compare two Fields (Wich Stores Date) and than Add To a third Filed the Max(Field1,Field2)
this had looked to my a simple thing to do, but unfortunately working with date is more difficult than I'd expected;
I've tryed something like this:

Sub pi()
Dim rst As DAO.Recordset
Dim dif As Long
DTCMPT As DateTime
DTDEBEF As DateTime


Set rst = CurrentDb.OpenRecordset("Step1", dbOpenDynaset)
With rst
Do Until .EOF
dif = DateDiff(DTCMPT, DTDEBEF)
If dif <= 0 Then
.Edit
!MDATE = !DTCMPT
.Update
Else
.Edit
!MDATE = !DTDEBEF
.Update
End If
.MoveNext
Loop
.Close
End With
Set rst = Nothing
End Sub



End Sub

but of course it doesen't work becouse the syntax is wrong. How can I adjust this to work????
Thank you all for your answares!!!!

This is incorrect:
The proper syntax for DataDiff is:
See Access Help System.

How can I declare that DTCMP , DTBEDEF, MDATE are the fields that I want to use to compare and update????

Try:

Thank you It Works Great

in actual fact you can take advantage of the way that Access / JET stores dates whichis numeric the most significiant digits represenbt the number of days since (IIRC 01 Jan 1900), and the decimal = proportion of days eg .5 = 12:00, .75 = 18:00, 0.0416666666666667 an hour)

so you could run two queries
eg
update mytable set mydatecolumn = date1 where date1 >= date2
update mytable set mydatecolumn = date2 where date2 >date1

or
update mytable set mydatecolumn = iif(date1>= date2, date1, date2)


mind you it does beg the question why you'd want to store such derived data as you can always find the correct date in the query by using the iif clause above. storing derived data is a no no..
why?
what happens if later on somebody changes the values of one or more date columns, then you have to rerun your process to set the new date.

there are times when you can and should store what at first glance seems derived data. ferinstance on an order, the order details probably should list the price the goods were sold at, the prevailing sales tax rate (or value), the order header should record the actual customer. so you do not want to change those items if say your sales tax rate goes up, the supplier changes or changes name and so on.

Thank you sooooo much!!!!
GrazieMille!!!!