Code first generating strange column - sql-server-2008

Question

I have an MVC 4 application that is using code first to generate tables and columns in my SQL Server DB. I am trying to figure out how I ended up with an additional TABLE that was not intended. I have looked through some questions but not found the exact same problem I am having. I will try to explain this simply.
I have added a model called Associate which keeps track of associates that my client does business with. Each Associate needs a foriegn key of AssociateTypedID and RegionID.
namespace XXX.Models
{
public class Associate
{
public int AssociateId { get; set; }
public string AssociateName { get; set; }
public int AddressNumber { get; set; }
public string AddressStreet { get; set; }
public string City { get; set; }
public string State { get; set; }
public string Zipcode { get; set; }
public string MainPhoneNumber { get; set; }
public string AssociateEmail { get; set; }
public string AssociateWebsite { get; set; }
public string ContactFirstName { get; set; }
public string ContactLastName { get; set; }
public string ContactPhoneNumber { get; set; }
public string ContactEmail { get; set; }
public int RegionId { get; set; }
public int AssociateTypeId { get; set; }
public virtual ICollection<AssociateType> AssociateTypes { get; set; }
public virtual ICollection<Region> Regions { get; set; }
}
}
AND
namespace XXX.Models
{
public class AssociateType
{
public int AssociateTypeId { get; set; }
public string AssociateTypeName { get; set; }
public virtual ICollection<Associate> Associates { get; set; }
}
}
AND
namespace XXX.Models
{
public class Region
{
public int RegionId { get; set; }
public int RegionName { get; set; }
public int RegionDescription { get; set; }
public virtual ICollection<Associate> Associates { get; set; }
}
}
AND
namespace XXX.Models
{
public class XXXDb : DbContext
{
public XXXDb(): base("name=DefaultConnection")
{
}
public DbSet<Associate> Associates { get; set; }
public DbSet<AssociateType> AssociateTypes { get; set; }
public DbSet<Region> Regions { get; set; }
}
}
So I have updated my code above and I'm getting very close to where I need to be in my database. I have the following tables generated.
Associates, AssociateTypes & Regions (each of them have the columns I would expect)
BUT I now have a new table called RegionAssociates which has the following columns:
Region_RegionId (int) & Associate_AssociateId (int)
This table was not expected or needed in my schema.

Answer 1

Your classes doesn't match your description of the model. You are saying
Each Associate can have a designation of AssociateType
I suppose that the same AssociateType can be assigned to more Associates, so there should be 1:N relationship between AssociateType and Associate.
But the Associate class defines the relationship the other way around - by convention public virtual ICollection<AssociateType> AssociateType { get; set; } creates 1:N relationship between Associate and AssociateType.
the correct definition of your classes would be
public class Associate
{
public int AssociateId { get; set; }
public string AssociateName { get; set; }
public int AddressNumber { get; set; }
public string AddressStreet { get; set; }
public string City { get; set; }
public string State { get; set; }
public string Zipcode { get; set; }
public string MainPhoneNumber { get; set; }
public string AssociateEmail { get; set; }
public string AssociateWebsite { get; set; }
public int RegionId { get; set; }
public int AssociateTypeId { get; set; }
public virtual AssociateType AssociateType { get; set; }
public string ContactFirstName { get; set; }
public string ContactLastName { get; set; }
public string ContactPhoneNumber { get; set; }
public string ContactEmail { get; set; }
public virtual ICollection<Region> Regions { get; set; }
}
public class AssociateType
{
public int AssociateTypeId { get; set; }
public string AssociateTypeName { get; set; }
public virtual ICollection<Associate> Associates { get; set; }
}

Answer 2

Can't say for sure what is missing from your configuration as you did't post it, but if you are using the fluent api something like this should fix the problem:
modelBuilder.Entity<AssociateType>()
.HasKey(t => t.AssociateTypeId);
modelBuilder.Entity<Associate>()
.HasRequired(t => t.AssociateType)
.WithRequiredPrincipal(t => t.Associate);
The above is adapted from this article http://msdn.microsoft.com/en-us/data/jj591620.aspx