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tomislavg
Yak Posting Veteran

51 Posts

Posted - 2010-01-22 : 03:17:29
Dear All,

I need to make my current SQL DB operate on the laptop in the field, where there is no connections. Is there any way that my frontend application (SQL backend) can store data and when needed synchronizing it with SQL on the network? Use express edition for laptop? or somehowe have tables linked or...?

Thanks,
Tomislav

Lumbago
Norsk Yak Master

3271 Posts

Posted - 2010-01-22 : 03:36:57
Look in to Merge Replication...it is designed to do exactly what you are requesting.

- Lumbago
http://xkcd.com/327/
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tomislavg
Yak Posting Veteran

51 Posts

Posted - 2010-01-22 : 03:50:58
Thanks a lot Lumbago, I will check.
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Lumbago
Norsk Yak Master

3271 Posts

Posted - 2010-01-22 : 04:05:19
As you might understand, depending on your database design it could be really simple to set up or really difficult. And the tricky part is to figure out how to handle conflicting data changes; what happens when/if your disconnected laptop updates the same data as your front end? Merge replication has built in conflict resolution but when it comes down to it, it's a matter of business rules reall...someone will have to win the conflict.

- Lumbago
http://xkcd.com/327/
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Kristen
Test

22859 Posts

Posted - 2010-01-22 : 04:41:35
Good post Lumbago
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Lumbago
Norsk Yak Master

3271 Posts

Posted - 2010-01-22 : 06:38:48
Thanx :) I have to admit I have no first hand knowledge in the area but as you know I've been doing some reading for my certification... :)

- Lumbago
http://xkcd.com/327/
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tomislavg
Yak Posting Veteran

51 Posts

Posted - 2010-01-22 : 07:05:35
Good point, should I use SQL Express on the laptop or should I just link tables through the application...or..?
Of course I will read about it, but just to get the general idea which way to go, it would help a lot.
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Lumbago
Norsk Yak Master

3271 Posts

Posted - 2010-01-22 : 07:29:07
This article will give you an excellent intro to merge replication:

http://technet.microsoft.com/en-us/library/ms151323.aspx

But the really short version is that you have a central server (publisher) and multiple remote disconnected devices (called subscribers, express edition is supported; check this link for full feature list: http://msdn.microsoft.com/en-us/library/cc645993.aspx). And once the subscriber gets online you start a sync job (often started manually) that sends data back to the publisher and recieves new data that has been updated by someone else.

- Lumbago
http://xkcd.com/327/
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russell
Pyro-ma-ni-yak

5072 Posts

Posted - 2010-01-22 : 07:32:18
quote:
Originally posted by tomislavg

I need to make my current SQL DB operate on the laptop in the field, where there is no connections.


quote:
Originally posted by tomislavg

should I use SQL Express on the laptop or should I just link tables through the application...or..?


I think you know the answer to this. What happens to a linked tables when the server is not available?

Also, linked tables are EVIL. Shun them, hunt them down and KILL THEM. Then go find the developer(s) who created them and mock and ridicule them.
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tomislavg
Yak Posting Veteran

51 Posts

Posted - 2010-01-22 : 07:56:56
quote:
Originally posted by russell

quote:
Originally posted by tomislavg

I need to make my current SQL DB operate on the laptop in the field, where there is no connections.


quote:
Originally posted by tomislavg

should I use SQL Express on the laptop or should I just link tables through the application...or..?


I think you know the answer to this. What happens to a linked tables when the server is not available?

Yeap, not too much use of them when there is no connection....let me renew my basics... :-)


Also, linked tables are EVIL. Shun them, hunt them down and KILL THEM. Then go find the developer(s) who created them and mock and ridicule them.
Hmmm... some people relly prefer them....




Thanks for the sites and explanations Lumbago, this is exactly what I was looking for....

So now I have to get started.....arranging and preparing everything....
Thanks everybody
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