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BOOK: Beginning ASP.NET 4 : in C# and VB
This is the forum to discuss the Wrox book Beginning ASP.NET 4: in C# and VB by Imar Spaanjaars; ISBN: 9780470502211
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Old January 10th, 2011, 05:48 PM
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Default How many linq-to-SQL datacontexts per solution? I get the “menber is defined more tha


I get the “menber is defined more than once” error. I have a relational database with about 15 tables that will be used in 4 different aspx pages (for now). Each aspx page uses some of the tables, but never all tables at once: for instance, one page might use 4 tables while another page might use 6 tables. I started doing a dbml file for the first aspx file with just the 4 tables needed. When I got to the second aspx file, I did another dbml file with just the 6 tables that were needed for this aspx file. 2 of the tables are in both datacontext dbml files and I get a "member is defined more than once" error.

After reading some online posts, my question about dbml files is this: when using linq-to-SQL, for an application, can we create multiple dbml files with the same tables or do we have to do just one dbml file for the whole application because a table can only be in one dbml file. If the latter is the case, do we need to simply include every database table in the dbml file and then always use the same datacontext throughout the project.

Old January 11th, 2011, 01:57 PM
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Hi there,

Can you please post questions that are not directly related to this book in a more general ASP.NET category here: http://p2p.wrox.com/asp-net-asp-12/ ? Makes it easier for others to join and learn from the discussion.

Anyway, you can differentiate types in different DBML files by setting the Entity Namespace property of the model (click the design surface and then press F4).

However, with only 15 tables, I would add them all to a single DBML file.

and then always use the same datacontext throughout the project.
The same datacontext *type*, not the actual instance. That is, you want to "new" up a context in each page, and not use a global one that all your pages use.


Imar Spaanjaars
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Author of Beginning ASP.NET 4.5 : in C# and VB, Beginning ASP.NET Web Pages with WebMatrix
and Beginning ASP.NET 4 : in C# and VB.
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Old January 11th, 2011, 02:11 PM
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Default ok, thank you for your reply.

ok, thank you for your reply.

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