Change the connection string dynamically for edmx entity during run time

1. Create a database using the script in “Change the connection string dynamically for SQLDataSource during run time”.


2. Create a console project


3. Create an entity with customer table, the steps to create entity as shown in “Back to basic (Part 1)”.


4. Duplicate the connection string from app.config and edit it.


<add name=OMSEntities1 connectionString=metadata=res://*/OMS.csdl|res://*/OMS.ssdl|res://*/OMS.msl;

provider=System.Data.SqlClient;provider connection string=&quot;Data Source=.;Initial Catalog=OMSMS;Integrated Security=True;MultipleActiveResultSets=True&quot; providerName=System.Data.EntityClient />


5. Enter the code as below.


static void Main(string[] args)


  OMSEntities context = new OMSEntities();

  //select customer to c

  var cus = from c in context.Customers select c;

  //Get the connection string

  string strConn = ConfigurationManager.ConnectionStrings[“OMSEntities1”].ConnectionString;

  //overload the edmx default constructor

  OMSEntities context1 = new OMSEntities(strConn);

  var c1 = from c in context.Customers select c;     




Download the complete code from The sample file name is ConAppDynamicEdmx.rar. My MSN ID is


About chanmingman

Since March 2011 Microsoft Live Spaces migrated to Wordpress ( till now, I have is over 1 million viewers. This blog is about more than 50% telling you how to resolve error messages, especial for Microsoft products. The blog also has a lot of guidance teaching you how to get stated certain Microsoft technologies. The blog also uses as a help to keep my memory. The blog is never meant to give people consulting services or silver bullet solutions. It is a contribution to the community. Thanks for your support over the years. Ming Man is Microsoft MVP since year 2006. He is a software development manager for a multinational company. With 25 years of experience in the IT field, he has developed system using Clipper, COBOL, VB5, VB6, VB.NET, Java and C #. He has been using Visual Studio (.NET) since the Beta back in year 2000. He and the team have developed many projects using .NET platform such as SCM, and HR based applications. He is familiar with the N-Tier design of business application and is also an expert with database experience in MS SQL, Oracle and AS 400.
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