Yes, I am storing the sequence in the data, and yes, there are times when multi things are generated at the same [Date] and [Time] but other fields like [Record Type] and [Status] will be included in subsequent queries to help as needed.
so you are saying it doesn't matter if two records have the same sequence number?
if you are using an update query you probably need to use the dcount function which will be even slower.
As in any audit trail, one thing happens before another and adding this sequence number to the data makes is easy to select the components in a needed order.
Since the order is dictated by the date/time, what is the benefit of a sequence number when you already have date/time?
It is not clear from your example data - is date and time one field or two?
assuming it is one field and you don't mind duplicate sequence numbers then you can try something like this
Code:
UPDATE myTable
SET SeqNo=dcount("*","myTable","OrderNo=" & [OrderNo] & " AND DateTime<=#" & Format(DateTime,"mm/dd/yyyy") & "#")
Be prepared - it could take some time.