Will Jet work for this?

[Maleus the Mighty]

Hi folks,

I have a task to write an application that requires a database backend. At
most I will have 5 or so concurrent users, and perhaps 30 users total. I
need to store the database file(s) at a UNC location on the network that's
backed up regularly, but I can't rely on IT to maintain a database service
there. Is it possible to use the Jet driver (the app will be written in
MFC) from different client machines to simultaneously access this single
database file? Or perhaps I should look at a different database? SQLite?

I'm not yet knowledgeable with databases so I'm looking at this problem from
different angles with the help of some you very smart folks. My apologies
if this is the wrong newsgroup.

Thanks much,
JJ

[Larry Linson]

Re: Will Jet work for this?

"Maleus the Mighty" <maleus@olympus .netwrote

Is it possible to use the Jet driver (the app will
be written in MFC) from different client machines
to simultaneously access this single database file?

Jet is a "file-server" database and always works exactly the way you want...
the database engine and Access (or runtime) are on the user's machine and
use the "backend" file on the shared disk just as though it were on the
local hard drive. Neither Jet nor Access need be installed on the machine
where the shared back-end resides. Each of the users, however, must have
full permissions on the disk or folder where the data resides -- including
create and delete file, update, read, write, and delete records. And the
back-end database is limited to 2GB total size.

* back-end = an .MDB shared tables with data, and relationships

Or perhaps I should look at a different database? SQLite?

If by SQLite, you mean the Express version of Microsoft SQL Server, no,
because all versions of Microsoft SQL Server (including the MSDE version
that shipped with Access in the past) are server databases... that is, the
database engine runs on the server where the data resides. If "SQLite" is a
third-party product, I couldn't answer, because I'm unfamiliar with it; but
I'd say the question is moot because Jet does exactly what you want.

Larry Linson
Microsoft Office Access MVP

[Maleus the Mighty]

Re: Will Jet work for this?

"Larry Linson" <bouncer@localh ost.notwrote in message
news:OsyDj.2702 $bN3.1486@trndd c03...

"Maleus the Mighty" <maleus@olympus .netwrote
>

Is it possible to use the Jet driver (the app will
be written in MFC) from different client machines
to simultaneously access this single database file?

>
Jet is a "file-server" database and always works exactly the way you
want... the database engine and Access (or runtime) are on the user's
machine and use the "backend" file on the shared disk just as though it
were on the local hard drive. Neither Jet nor Access need be installed on
the machine where the shared back-end resides. Each of the users,
however, must have full permissions on the disk or folder where the data
resides -- including create and delete file, update, read, write, and
delete records. And the back-end database is limited to 2GB total size.
>
* back-end = an .MDB shared tables with data, and relationships
>
... Larry Linson
Microsoft Office Access MVP

Thank you! I had hoped this would be an acceptible approach given the nice
MFC wrappers and redistributable nature of Jet.

Would the MDB file simply be locked during access, or is a more
sophisticated integrity scheme possible? I have a low number of concurrent
users but I'd like consider network latency against the speed of particular
queries/writes/etc.

-JJ

[timmg]

Re: Will Jet work for this?

When the first user's front end connects to the back end .mdb Access
creates a lock file with the name of the back end file and the
extension .ldb. That's where Access manages locks and whatnot for
subsequent users. That's why users need write privledges to the
directory holding the back end file.

I hope that's what you mean by "sophistica ted integrity scheme." I've
had great sucess with dozens of simultanious user happily creating and
editing records.

Good luck!

Tim Mills-Groninger

...

Would the MDB file simply be locked during access, or is a more
sophisticated integrity scheme possible?  I have a low number of concurrent
users but I'd like consider network latency against the speed of particular
queries/writes/etc.

...

[Maleus the Mighty]

Re: Will Jet work for this?

Exactly what I meant. Time to play with a prototype. Thanks much for the
help!

-JJ

------------------------------------

When the first user's front end connects to the back end .mdb Access
creates a lock file with the name of the back end file and the
extension .ldb. That's where Access manages locks and whatnot for
subsequent users. That's why users need write privledges to the
directory holding the back end file.

I hope that's what you mean by "sophistica ted integrity scheme." I've
had great sucess with dozens of simultanious user happily creating and
editing records.

Good luck!

Tim Mills-Groninger

....

Would the MDB file simply be locked during access, or is a more
sophisticated integrity scheme possible? I have a low number of concurrent
users but I'd like consider network latency against the speed of
particular
queries/writes/etc.

....

[David W. Fenton]

Re: Will Jet work for this?

"Maleus the Mighty" <maleus@olympus .netwrote in
news:Mu2dnQyzKu DUvULanZ2dnUVZ_ uGknZ2d@scnrese arch.com:

Reasonable idea that I'd certainly pursue if not for a front-end
that requires interfacing certain bits of proprietary hardware.

No COM-based interfaces for those? If so, then an MDB will be just
fine.

--
David W. Fenton http://www.dfenton.com/
usenet at dfenton dot com http://www.dfenton.com/DFA/

[Maleus the Mighty]

Re: Will Jet work for this?

>Reasonable idea that I'd certainly pursue if not for a front-end

>that requires interfacing certain bits of proprietary hardware.

>
No COM-based interfaces for those? If so, then an MDB will be just
fine.
>
--
David W. Fenton http://www.dfenton.com/
usenet at dfenton dot com http://www.dfenton.com/DFA/

COM or not, it wouldn't matter. Still going with MFC/C++ for the front-end.
But my prototyping indicates an MDB back-end will work just fine.

Thanks to all, this newsgroup has been especially helpful.

-JJ

[Tony Toews [MVP]]

Re: Will Jet work for this?

"Maleus the Mighty" <maleus@olympus .netwrote:

>Reasonable idea that I'd certainly pursue if not for a front-end that
>requires interfacing certain bits of proprietary hardware.

Does the hardware come with DLLs what you can use in VB? If so they should port over
to VBA quite nicely.

Tony
--
Tony Toews, Microsoft Access MVP
Please respond only in the newsgroups so that others can
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