Running total for elapsed time?

[Fuzzy Logic]

I have a table with the relevant fields being Number, StartTime, EndTime. I
wish to produce a query that will display the Number, difference in time and
a running total for the difference in time per number. For example:

1 0:30 0:30
1 0:15 0:45
1 1:00 1:45
2 0:15 0:15
2 0:30 0:45
2 1:15 2:00

I've had no problem calculating the time difference based on start and end
time but cannot figure out how to get the running total. Any help would be
greatly appreciated.

 

[Allen Browne]

Since the order of records is important here, you will need some field (such
as an autonumber) that defines the order of records.

Create a query into this table. Type a subquery into a fresh column in the
Field row. Something like this:
Minutes: (SELECT Sum(DateDiff("n", Dupe.StartTime, Dupe.EndTime))
FROM Table1 AS Dupe
WHERE (Dupe.ForeignID = Table1.ForeignID)
(AND Dupe.ID <= Table1.ID))

Assumes:
- table named Table1;
- foreign key named ForeignID (the 1, and 2 in your example below);
- primary key named ID (the new autonumber);
- a read-only result is okay;
- display in minutes is okay.