Dates have no format when they are stored in the database: the date format is something that helps human beings interpreting the date, but in the database they are stored...

It is already like that. What are you trying to achieve?

This URL worked for me: https://support.microsoft.com/en-us/kb/982441

A few minutes are ok to sync via merge replication. It only sends the delta, so it looks like a perfect fit for your case.

OK, sorry if I insist...

1) if they send via email, at some point the machines are connected to a network that could allow the sync

2) sending via email means...

How do they provide the backup file to you? I suppose there is some connectivity involved at some point

There is a way to allow connection of Merge Replication subscribers through a web application in IIS. It's called web synchronization: https://msdn.microsoft.com/en-us/library/ms151763.aspx

If you can't delete the files, something is using them.

Are you sure that it's the right files? Try looking at sys.master_files: does any of those files appear here?

Merge Replication is designed for subscribers staying offline for long periods. Merge Replication is available in all versions of SQL Server since 2000 if I recall correctly. It definitely is...

Merge replication is a data distribution technology that is used to keep multiple subscribers in sync with a publisher.

Each row is marked with a unique GUID that is used to...

Open SQL Server configuration manager, locate the services, edit the logon credentials and restart the services.

Have you tried looking into Merge Replication? Looks like a perfect fit for your problem.

I don't see where the "Quantity" column comes from. Is that the actual query you're running or a simplified version?

However, the message indicates that you're comparing the column "Quantity" (which...

It would be the contrary to be proven: it's not a Russell's teapot.

Absolutely not. Network issues do not trigger anything on the procedure cache.