Make the primary key have 2 fields, the new one being an indicator of who made the
changes.

Then use an import routine to merge the databases.

If changes may be made to the same records then you'll have to decide what to do with
them.

If changes have been made to lookup tables then you'll have more work to do.

Regards,
Raymond.

pkh2001fi wrote:

>
> Hello,
>
> I'm writing a rather complex project management system (with
> Firebird/IBO) for a customer. This customer want's to "outsource"
> some of the planning, that is, give the software and a copy of their
> database to another company and then, when the company has finished
> their work, syncronize the changed database with their own "main"-
> database.
>
> The problem is the primary keys. Each table has a primary key of
> integer-type and get's its value from a table-specific generator. A
> lot of the tables also contain lookup-key values that reference other
> tables.
>
> I don't know how to implement the syncronization system, without
> risking key violations. What happens if the third-party company adds
> records to a table while the "main"-customer makes changes to the
> same table? Then there are two records with different data, but with
> the same primary key.
>
> Another problem, which is in my opinion more complicated, is if the
> third-party company creates a new record in one of the lookup tables,
> which is referenced by another record. If the "main"-customer also
> creates a new record in the same lookup table, there is not only a
> primary key violation, but also a "lookup-key-violation", if you see
> what I mean.
>
> Frankly I don't know how to solve this problem, and I hope I've
> managed to explain the problem clearly enough. Any help is very much
> appreciated.
>
> Should I create some kind of table locking which prevents the main
> customer from editing those parts of the database that are
> currently "out-sourced"?
> I have a changelog system which logs all inserts, updates and deletes
> in all the tables. Could I perhaps use this system and just overwrite
> any existing records added after the export date?
>
> Thanks in advance,
>
> -Petter-
>
>
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