Switching between databases in Windows forms

Neven Draskovic

Hey
I made an application that generates reports based on data from a database. The functionality of my application is correct, but I have a following problem: my client has 2 identical databases - one for testing and one for actual work he does. My application should work with both databases (it should have a "switching mechanism"), but I don't know how to implement it. I know that I could just switch between connection strings but the problem is that in my reports I use datasets that are bound to one database. Is it possible to fill those datasets with the data from both databases (since the databases are identical in schema, it should be possible), and how would that be done, or do I have to use duplicate dataset/report pairs?
I'm using C# in VS 2010 with SQL Server 2005, and .rdlc for my reports.
Thanks.

3 Replies

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Vulpes14y ago
If you're not bothered about writing any updates back to the databases, then you might be able to merge those DataTables with similar schemas into a single DataTable and then link your report to that:

http://msdn.microsoft.com/en-us/library/system.data.datatable.merge.aspx

Otherwise, you could try to get the second DataAdapter to fill the DataTable already created by the first DataAdapter. However, I suspect that either it won't work at all, it will work but the existing rows will be overwritten or it will appear to work but you'll end up with a mess when you try to write updates back to the relevant sources.
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Neven Draskovic14y ago
Well that is just what I'm trying to avoid - because if I use different DataTables, I will have to create different reports, because each report uses those DataTables (I created them by using the report wizard, I don't know how to change them programmatically). I found out that I can change the used connection string in the app.config file, and that works, I now need to find out how to change that file depending on the selected database (the user changes it by picking one option out of the comboBox). Do you have some comment/suggestion on this approach?
Thanks
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Vulpes14y ago
It is possible to fill a DataSet with data from two or more databases by using a separate DataAdapter for each one. The DataAdapters can then be initialized with their own SQL queries and connection objects.

Each database needs to fill its own DataTable(s) within the DataSet so updates can be posted back to the correct source.

There's an example below on MSDN which should get you on the right track:

http://msdn.microsoft.com/en-us/library/bh8kx08z.aspx
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