R – How To Remove Foreign Key Reference In Entity Framework

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I'm updating my model which is built by entity framework. I removed a entity from the designer and then there pops up a error said "Foreign key constraint 'FK_Table1_Table2' … no mapping specified for the table Table2. Now I really don't want to map Table2 into entities. What should I do to clear the edmx and avoid such error? Can I just map the foreign key in Table1 into a int32 field? Thanks!

I'm using EFv1.

Best Answer

I've found the Entity Framework designer leaves a lot to be desired so I found the best way is to edit the .edmx by hand.

The .edmx file contains 3 main sections, one which represents the storage model (database), one which represents the conceptual model and one section which represents the mapping between the two models

If I understand correctly, you have removed Table2 from the conceptual model and so you should remove anything related to it in the conceptual side of the EDMX. Chances are table 1 will still have an association to table 2 that you need to delete. Unfortunately manual edits to the .EDMX file will be overwritten if you ever use the designer to regenerate the model.

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.net – Entity Framework vs LINQ to SQL

LINQ to SQL only supports 1 to 1 mapping of database tables, views, sprocs and functions available in Microsoft SQL Server. It's a great API to use for quick data access construction to relatively well designed SQL Server databases. LINQ2SQL was first released with C# 3.0 and .Net Framework 3.5.

LINQ to Entities (ADO.Net Entity Framework) is an ORM (Object Relational Mapper) API which allows for a broad definition of object domain models and their relationships to many different ADO.Net data providers. As such, you can mix and match a number of different database vendors, application servers or protocols to design an aggregated mash-up of objects which are constructed from a variety of tables, sources, services, etc. ADO.Net Framework was released with the .Net Framework 3.5 SP1.

This is a good introductory article on MSDN: Introducing LINQ to Relational Data

Entity-framework – How to view the SQL generated by the Entity Framework

For those using Entity Framework 6 and up, if you want to view the output SQL in Visual Studio (like I did) you have to use the new logging/interception functionality.

Adding the following line will spit out the generated SQL (along with additional execution-related details) in the Visual Studio output panel:

using (MyDatabaseEntities context = new MyDatabaseEntities())
{
    context.Database.Log = s => System.Diagnostics.Debug.WriteLine(s);
    // query the database using EF here.
}

More information about logging in EF6 in this nifty blog series: http://blog.oneunicorn.com/2013/05/08/ef6-sql-logging-part-1-simple-logging/

Note: Make sure you are running your project in DEBUG mode.

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.net – Entity Framework vs LINQ to SQL

Entity-framework – How to view the SQL generated by the Entity Framework

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