// Configure the primary key for the OfficeAssignment
modelBuilder.Entity<OfficeAssignment>() .HasKey(t => t.InstructorID); // Map one-to-zero or one relationship
modelBuilder.Entity<OfficeAssignment>() .HasRequired(t => t.Instructor) .WithOptional(t => t.OfficeAssignment);

// Configure the primary key for the OfficeAssignment
modelBuilder.Entity<OfficeAssignment>() .HasKey(t => t.InstructorID); modelBuilder.Entity<Instructor>() .HasRequired(t => t.OfficeAssignment) .WithRequiredPrincipal(t => t.Instructor);

modelBuilder.Entity<Course>() .HasMany(t => t.Instructors) .WithMany(t => t.Courses)

modelBuilder.Entity<Course>() .HasMany(t => t.Instructors) .WithMany(t => t.Courses) .Map(m => { m.ToTable("CourseInstructor"); m.MapLeftKey("CourseID"); m.MapRightKey("InstructorID"); });

// Configure the primary Key for the OfficeAssignment
modelBuilder.Entity<OfficeAssignment>() .HasKey(t => t.InstructorID); modelBuilder.Entity<Instructor>() .HasRequired(t => t.OfficeAssignment) .WithRequiredPrincipal();

modelBuilder.Entity<Course>() .HasRequired(t => t.Department) .WithMany(t => t.Courses) .HasForeignKey(d => d.DepartmentID) .WillCascadeOnDelete(false);

// Composite primary key
modelBuilder.Entity<Department>()
.HasKey(d => new { d.DepartmentID, d.Name }); // Composite foreign key
modelBuilder.Entity<Course>()  .HasRequired(c => c.Department)  .WithMany(d => d.Courses) .HasForeignKey(d => new { d.DepartmentID, d.DepartmentName });

modelBuilder.Entity<Course>() .HasRequired(c => c.Department) .WithMany(t => t.Courses) .Map(m => m.MapKey("ChangedDepartmentID"));

modelBuilder.Entity<Course>() .HasRequired(c => c.Department) .WithMany(d => d.Courses) .HasForeignKey(c => c.SomeDepartmentID);

using System.Data.Entity;
using System.Data.Entity.ModelConfiguration.Conventions;
// add a reference to System.ComponentModel.DataAnnotations DLL
using System.ComponentModel.DataAnnotations;
using System.Collections.Generic;
using System; public class SchoolEntities : DbContext
{ public DbSet<Course> Courses { get; set; } public DbSet<Department> Departments { get; set; } public DbSet<Instructor> Instructors { get; set; } public DbSet<OfficeAssignment> OfficeAssignments { get; set; } protected override void OnModelCreating(DbModelBuilder modelBuilder) { // Configure Code First to ignore PluralizingTableName convention // If you keep this convention then the generated tables will have pluralized names. modelBuilder.Conventions.Remove<PluralizingTableNameConvention>(); }
} public class Department
{ public Department() { this.Courses = new HashSet<Course>(); } // Primary key public int DepartmentID { get; set; } public string Name { get; set; } public decimal Budget { get; set; } public System.DateTime StartDate { get; set; } public int? Administrator { get; set; } // Navigation property public virtual ICollection<Course> Courses { get; private set; }
} public class Course
{ public Course() { this.Instructors = new HashSet<Instructor>(); } // Primary key public int CourseID { get; set; } public string Title { get; set; } public int Credits { get; set; } // Foreign key public int DepartmentID { get; set; } // Navigation properties public virtual Department Department { get; set; } public virtual ICollection<Instructor> Instructors { get; private set; }
} public partial class OnlineCourse : Course
{ public string URL { get; set; }
} public partial class OnsiteCourse : Course
{ public OnsiteCourse() { Details = new Details(); } public Details Details { get; set; }
} public class Details
{ public System.DateTime Time { get; set; } public string Location { get; set; } public string Days { get; set; }
} public class Instructor
{ public Instructor() { this.Courses = new List<Course>(); } // Primary key public int InstructorID { get; set; } public string LastName { get; set; } public string FirstName { get; set; } public System.DateTime HireDate { get; set; } // Navigation properties public virtual ICollection<Course> Courses { get; private set; }
} public class OfficeAssignment
{ // Specifying InstructorID as a primary
    [Key()] public Int32 InstructorID { get; set; } public string Location { get; set; } // When the Entity Framework sees Timestamp attribute // it configures ConcurrencyCheck and DatabaseGeneratedPattern=Computed.
    [Timestamp] public Byte[] Timestamp { get; set; } // Navigation property public virtual Instructor Instructor { get; set; }
}