Let’s take a look at the error message that we receive when we do a concurrent update on an In-Memory OLTP (Hekaton) table. I start by opening a connection and running:

begin transaction
 
update CheckingAccount with (snapshot)
set    Balance = 100.00
where  OwnerId = 123;

This update runs fine. Now, after this first statement completes, I open a second connection and run another update against the same table:

update CheckingAccount
set    Balance = 200.00
where  OwnerId = 123;

Since I have an open transaction in the first connection that has updated the same row, I expect the second attempt to fail. It does, and the error message is:

Msg 41302, Level 16, State 110, Line 1
The current transaction attempted to update a record that has been updated since this transaction started. The transaction was aborted.
The statement has been terminated.

The wording of this error message is a bit misleading, however. Clearly the first update did not happen after the second transaction started, particularly given that the second connection had not yet even been established at that time!