Tag Archives: Entity Framework 6

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Cannot drop database because it is currently in use

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This is a common scenario and there are lots of posts on this. The following works for me:

My database is  located on a virtual machine running Server 2012 and SQL Server 2012 under Hyper-V locally on my development machine.

In SQL Server Management Studio In the  object explorer pane right click the database and select “Detach” from the context menu. Check “Drop” in the resulting dialog:

Drop SQL Connections

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Configure 1:1 relationship in code first

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When I tried to load some test data into a database I’d just created in code first I hit the following error:

“a dependent property in a referential constraint is mapped to a store-generated column. column ‘id’

Example loading code:

   1:  myDbContext.Accounts.Add(
   2:     new Accounts{
   3:         Name = "Account #1",
   4:                 ReferenceData = new Entity2
   5:                                     {
   6:                                        RefLocator = "Ref #1"
   7:                                      }
   8:                 })

I eventually configured the POCO classes for the two entities as follows:

   1:  namespace Test.Model
   2:  {
   3:      [Table("Account")]
   4:      public class Account
   5:      {
   6:          [Key, ForeignKey("ReferenceData")]
   7:          public Guid Id { get; set; }
   8:          public string Name { get; set; }
   9:          public ReferenceData ReferenceData { get; set; }
  10:   
  11:      }
  12:      [Table("ReferenceData")]
  13:      public class ReferenceData
  14:      {
  15:          [Key, ForeignKey("Account")]
  16:          public Guid Id { get; set; }
  17:          public string RefLocator { get; set; }
  18:   
  19:   
  20:      }
  21:  }

I tend to prefer using attributes to the fluent mapping when writing EF classes. 
Hopefully this saves someone a little time.