How can I calculate datediff between 2 records?

[ccIces]

Hello all,
I have a data table that lists user log ins sequentially by date. I need to write a function for use in a update query that will calculate the datediff in minutes between each change in user log in.
My table loogs like this
aaa123, stn1, 2005-08-08 12:00
bbb222, stn1, 2005-08-08 13:00
ccc333, stn1, 2005-08-08 14:00
and I need to end up with this:
aaa123, stn1, 2005-08-08 12:00 60(or time however it is expressed)
bbb222, stn1, 2005-08-08 13:00 60
ccc333, stn1, 2005-08-08 14:00 60

the way I figure it I need a function in my query similar to this
expr1: datediff( "n", starttime, endtime)
but I need to figure out how to put the end time in there which is the start time of the next record in the table.

 

[BryanT]

Hello ccIces

You could do all of the processing using a recordset and vba instead of in a query, then pass the required variables to your update query.

Bryan

 

[ccIces]

I can see the logic of how to do it, I need help telling that to the computer to make it happen.
I just can't seem to figure out how to subtract one records time from another. Can someone suggest a function that would grab the next records value so I can use it in the calculation?
The table fields are ID, Lane, Date
so I need something that
makes a recordset
takes the current record and store the date value to a variable
move to the next record and subtract that date value from the variable
show the resulting value in a new column in the same table.