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.net windows application store data offline and store to db when there is network

I am developing a windows application for agricultural purpose. This application will be used by multiple users to maintain the data. The main issue is there won't be network connectivity on the work location. But however by end of the day they can go and synchronize if there are any option.
I just want to know how can we import and store all the data locally and update the data to database when there is network.
The options that i thought is to have SQL on every machine that runs this application. Store the data to local database when there is no network.
Having a separate button to export the local data to the centralized database when there is network.
Looks like this is complicated. Is there any better and easier option.
I prefer using c#, Visual studio.
Thanks.

You can use SQLite for storing data locally. It's fast, lightweight, and public domain.
You can use whatever the database of choice for the centralized server.

Well, this a quite broad question, as it has many options and scenarios. The questions you should ask yourself are:
Does user handle new information only or any information from any other user from the previous syncing?
Do you have to handle update conflicts?
Do you handle text information only or you have complex types and binary files?
As for the solution, the easiest way, from my point of view, would be using SQL Lite on portable devices, is a lightweight SQL client that will allow you to handle information easily. On the server you can use whatever you want, SQL Server, MySQL or any other SQL flavor you may like. Just make sure there is a connector for your portable device OS.
If you keep thinking of using SQL server on the portable device, it's a battery hogger!!!, you might want to check Microsoft Sync framework, as it provides almost all possible scenarios for handling data syncing, manage conflicts, etc.

Thanks for the answers. Please find the below solution that we implemented.
1) Installed SQL express on all the local machines
2) Used Microsoft Sync framework to sync the data. The sync is configured on demand.
Issues faced:
1) We were using geometry datatype on few tables and this was not supported by sync framework.
2) Any change in the database schema will not reflect on the client machine. We will have to delete all the system generated procedures used to track the table change and regenerate it. I am sure there will be a much better way to do this.
Cheers,
Jebli

Which one is the best method to replicate a database in SQL Server?

I was wondering which one is the best way to replicate some data of a database to another.
I have a database in one computer and this one receives some transactions. I need to send this data to another server (in the same local network) but with a modified value (I need to add 11 years to a Timestamp value).
So I was looking for some options for my case, I can develop a windows service to do this but I don't know if the sql server replication can do this for me or if there is another option like some kind of magical trigger that can do that.
I'm using SQL Server 2005 on Windows Server 2003 R2.

This link should help you:
Selecting the Appropriate Type of Replication
Quoted summary from link:
Microsoft SQL Server offers three types of replication. Each type of
replication is suited to different application requirements. Depending
on the needs of your application, you can use one or more types of
replication in a topology:
Snapshot replication
Transactional replication
Merge replication
I personally would replicate the database (transactional) and then use log shipping to update the replicated database (on your second server) with the latest data changes (from the primary server) then use a stored procedure running as a sql agent job to update the fields you need.
I personally am not a fan of triggers as you can end up having triggers activating other triggers and something that takes milliseconds to run can take seconds and if you have large volumes of data that can be painful (I manage a system that has exactly this issue - soon to be replaced thankfully)
hope this helps and if you have some follow up questions I'll be happy to help.

How can I store a lot of data locally for a program

I am current building (in C#) a fairly basic point-of-sale program for a local community in Uganda to use in tracking business at their sunflower seed press. I was thinking that I would need some sort of database (like a SQL database), but I've never set up a database before, so I'm wondering what the best way to do this is. Maybe a database isn't the best way. The program will not have internet access, so everything will have to be done locally on the machine.

I think your first step should be designing out what data you need to store. Build an Entity Relationship Model and decide what your domain model is going to be. There are many different Database Engines out there that you can use that have different features, installation requirements, etc. A database engine can be installed locally, or on a remote machine to connect to. If you're writing a C# app, you'll probably want to use the System.Data namespace. You can use plain ADO .NET, or use something like Linq To Enttiies to help create proxy classes for your data tables.
You can access a SQL database using the same API for queries / record extraction regardless of the DB Engine uses. In some caess, you may need to use a seperate library that provides an implementation (or a better one), as in the case of an Oracle Database and the Oracle Data Access Components. Right out of the gate, .NET works very well with Microsoft SQL Server, but other options would work.
The details of what database engine are not as important as defining a good set of data tables to represent your data.

Yes. If it has lots of data you have to consider using database. Whether you have internet or not, as long as you have local network, you can easily do database.
Set up a database server ( maybe sql)
Do your database and install it on the database server
Do your application and connect to your database through connection string.

You are on the right track to use a database to store data. It is pretty easy to accomplish. Your computer does not need to be connected to the internet.
SQL Server Express Edition is free with a limit of 10 gigs of data. This will probably be much, much more space than you will need.
From C#, use ADO.NET. It is very simple if you know some SQL. Code samples here.

Tools for Building an OCA (Occasionally Connected Application)

I will be building an in-house, Occasionally Connected App (OCA). What technologies would you suggest I employ.
Here are my parameters:
.NET Shop(3.5sp1)
C# for code behind (winform,wpf,silverlight)
SQL Server Backend (2005 or possibly 2008 pending approval)
Solo Developer
Solo SQL Administrator
Low Tech end users
Low bandwidth to 5 Branch offices
This is a LOB app but not a POS.
Majority of users have laptops that they take to Member's Home
The Data for this App is stored in 5 separate Databases, though in one SQL instance.
I am looking for specific recommendations on which path to choose. Merge Replication or Sync Framework database synchronization providers? SQL Express or SQL CE at the Subscriber? Can I use LINQ to SQL for the DAL?
Is a Silverlight 'Offline/Out of Browser App' Example Here, feasible?
This is my first LARGE business application so any experienced comments are welcome.
As requested here is some additional info on the type of Data. My users are Nurses and Social Workers who go to Member's homes and create "Plans" or "Health Assessment Reviews" for them. These are things like a Medication List or a List of there current "Providers". Steps to achieve members' goals or a list of there current/past Diagnosis's. Things like that.
Also the typical Members Name, Address, Phone Number, etc. Mostly this is a Data Storage and Retrieval app that facilitates reporting. Very little "processing" takes place and Nurses and Social Workers work in teams that are assigned members so I usually have very little crossover or potential data conflicts. Nurses and SW's also are responsible for different area's of the MCP(Member Centered Plan)
Additional question; Is Sync Framework really only a viable option if I can use SQL 2008? Seems that way due to the Change Tracking etc....thoughts?

Once you solve the problem of change detection and data movement, everything else is trivial. In other words technologies like WPF, Silverlight, Forms and even WCF are orthogonal to your main problem and your choice should be based on your personal preferences and experience. The real hard nut to crack is working disconnected and synchronizing changes. Which leaves two out-of-the-box avenues: Synch Framework or Replication.
I would say, for your scenario, definetely Synch Framework. Merge replication, like all forms of replication, is designed for systems that are connected continously with intermitent disconnects. And most critically replication can work only over static names. Laptops connecting from various hot-spots and ISPs have a nasty habit of changing FQ names with each connection. Replication can overcome this only if a VPN of sort is used and VPN is usually a major support issue. Replication is just not designed for the high mobility of OCA systems.
Synch Framework will pretty much force you to SQL 2008 back end because of the need to Change Data Capture or Change Tracking, both being SQL 2008 only features.
You will still have plenty of hard problems to solve ahead (authentication, versioning and upgrade, data conflict resolution policies, securing data on the client for accidental media loss etc etc)

Personally, I would say:
.NET 3.5
WCF Data Services (for communication between the client app and your data)
SQL Server 2k5/2k8 (whichever you can use)
Silverlight w/ Out of Browser Functionality
VistaDB (to store data locally on the client until you can push to the server)

use unique-identifier for key if you are creating stuff while offline and not connected and when you do connect, updating the database.
this is going to be way easier than using auto-increment key

Having worked on an occasionally connected application, I'd encourage you to look in to SQL Server CE for the client machines, with Sync Services to handle the connections. Here is a good tutorial.

You could create this stuff from the ground up, it seems.
However, this seems an awful lot like a CRM application, and it wouldn't surprise me if you could find an enterprise software package to do this without starting from scratch and instead modify one of the configurations to meet your business rules.
In a previous life, I was a configuration developer for this thing called Siebel that might be close to what your'e looking for. They even have a built-in synchronization tool called Siebel Remote.
It might be a cheaper route to go than rolling your own from scratch.

I wrote an order taking program for wine sales reps. Here is the video. The client software is installed using click-once. That also installs SQL Server Express and loads the database. I used the Microsoft Sync Framework to sync the local database with the one on the server (see the last section of the video.)
With powerful clients now I don't see any reason to not use SQL Server Express, it is free with a limit of 4GB.
SQL CE had too many limitations - no stored procs being a major one.
You will need to use GUIDs everywhere as the primary key - see the new NewSequentialID().
I love click-once, it is a big time saver.
I'm looking forward to Silverlight, but just haven't had time to look into it. Not sure if I would have done it with Silverlight if doing it now or not.
Having said all this, this is not a project for anyone inexperienced. So I would also get some very experienced help.

Any ORMs that work with MS-Access (for prototyping)?

I'm in the early stages of a project, and it's not clear yet whether we'll need a "real" database (i.e. SQL Server et al). So I've been doing some prototyping using MS-Access, which is working fine so far. (developing in C#/VS2008/.Net 3.5/MS-Access 2000).
However, the object-relational impedance mismatch is already becoming annoying, and will only get worse as the project evolves.
I have not been able to find an ORM that will work with MS-Access. Any suggestions?
Edit - Follow Up
We ended up using Fluent NHibernate, mainly because it Automaps our object model to a relational database, which has been a huge win for us. Most of the FNH code samples we found used SQLite, and this worked so well that we intend to use it for our production database. (The app is a desktop scientific data collection and analysis package).

MSAccess files can be set up as an ODBC source on Windows machines. Almost any ORM will allow you to use ODBC. Here is a quick tutorial on how to set that up, it's outlined for Win2k but the process is the same for XP+. You also need to have MDAC installed on your box.
NHibernate seems to have native support of MSAccess as well, see here. I've never used it though. It also has an ODBC driver.. Many others support ODBC as well.
And again, as others are saying.. MSAccess does not scale... period. Installing a real database server is fairly easy, so I'd recommend SQL Server Express as others have, or even MySQL or Postgre, whatever is easier to set up.
If this is an application that you intend to deploy to clients, with each client having their own unique database, I would recommend another solution entirely, SQLite. SQLite gives you database power on an app by app basis. If you have a central database server, one of the previously mentioned solutions would be best.

There's only one scenario when choosing the Access Database Engine is a good choice: when building a self-contained Access application using Access Forms (though choosing to use Access in the first place is a questionable choice ;)
The database engine that VS2008 plays nicest with is SQL Server and you will have no problem finding an ORM that plays nice with SQL Server.

Can't give you an answer to your question, but instead of Access you might want to consider one of the following options:
SQL Server Express: is free and compatible with the full SQL Server
SQL Server Compact: also free, does not require any deployment/installation, does not support all features (e.g. no stored procedures).

At this stage, if you are unsure whether you need a "real" database or not, I'd skip MS Access and go straight to sql server express. It's free and still allows you to do everything you need to.
Plus, if you later decide you need to scale up, then you can without any pain.

I recommend you to use something like Microsoft SQL Server or PostgreSQL for prototyping. If you don't want to learn specific SQL syntax and install special tools for designing database schema, you can use ORM that automatically generates database schema from your persistent classes declaration. Anyway this approach is very effective for prototyping.

LLBLGen works with Access

Access is just a bad, bad idea. I believe MS only includes Access in Office to keep legacy users happy.
Even if you find an ORM that will work with an Access database, with few exceptions you're locking yourself into a niche tool that likely will not work out-of-the box with a real database engine. If you decide to switch to a real database engine later on, you'll not only have to deal with migrating the database, but switching to a different ORM.
See this comparison between SQL Server Express and SQL Server Compact. The comparison document also mentions some problems with other data stores, including Access.
If you are REALLY concerned about being able to install SQL Server Express, consider SQL Server Compact:
it can be linked into your redistributable app. No need to install a service (which may require admin rights during install of your application); everything is taken care of when you install your app. This makes the most sense if you need the data to reside on the user's machine instead of a server, and is most analogous to using Access.
It's less powerful than Express (doesn't support views, triggers, stored procedures, which I consider a requirement)
Can be scaled up to Express or other SQL Server versions very easily
Suitable for small-footprint installs like tablets, mobile devices, etc.
Always keep scalability in mind when designing any application. You don't want to wind up having to write a PHP->C++ compiler if/when your app becomes successful just because you picked the wrong tool up front.
While we're at it:
The big issue with Access (or, in this case, the Jet engine, which is the part you'd really be using when integrating an Access database with a .NET app) is that there is no "server" that handles datase requests. The engine, hosted in your app, must read and write directly to a file on disk that contains the database. Whenever this happens, the file must be locked to prevent concurrent writes. Dirty reads become more common as the number of users grows, as does the potential for database corruption.
Imagine having every customer at a large restaurant trying to simultaneously enter the kitchen to write down their orders or retrieve their food. Chaos would result. There'd be a lot of broken dishes, the kitchen would be a mess, you'd be lucky to get what you ordered in any sort of edible condition. With one customer, this probably works fine. With 5, eh, maybe. With 20,50,1000? Not so much.
So, the restaurant industry introduced waiters and managers that buffer IO to the kitchen. The database server application does something roughly analogous to this by restricting access to the files on disk. Everyone gets what they want, faster and in a much more reliable way, and the data store is protected.