public class Business{[Key]public int BusinessId { get; protected set; }public string Name { get; set; }public string LicenseNumber { get; set; }}public class Retail : Business{public string Address { get; set; }public string City { get; set; }public string State { get; set; }public string ZIPCode { get; set; }}    public class eCommerce : Business{public string URL { get; set; }}public class BusinessesContext : DbContext{public DbSet<Business> Businesses { get; set; }protected override void OnModelCreating(DbModelBuilder modelBuilder){base.OnModelCreating(modelBuilder);modelBuilder.Entity<Business>().Property(b=>b.BusinessId).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);modelBuilder.Entity<Business>().ToTable("Business", "halower");modelBuilder.Entity<Retail>().ToTable("Retail", "halower");modelBuilder.Entity<eCommerce>().ToTable("eCommerce", "halower");}}

 private static void Main(string[] args){using (var context = new BusinessesContext()){var retail = new Retail{Name = "Shop and Save",LicenseNumber = "200C",Address = "101 Main",City = "Anytown",State = "TX",ZIPCode = "76106"};context.Businesses.Add(retail);var web = new eCommerce{Name = "BuyNow.com",LicenseNumber = "300AB",URL = "www.buynow.com"};context.Businesses.Add(web);context.SaveChanges();}using (var context = new BusinessesContext()){Console.WriteLine("\n--- All Businesses ---");foreach (var b in context.Businesses){Console.WriteLine("{0} (#{1})", b.Name, b.LicenseNumber);}Console.WriteLine("\n--- Retail Businesses ---");//OfType<T>:根据指定类型筛选foreach (var r in context.Businesses.OfType<Retail>()){Console.WriteLine("{0} (#{1})", r.Name, r.LicenseNumber);Console.WriteLine("{0}", r.Address);Console.WriteLine("{0}, {1} {2}", r.City, r.State, r.ZIPCode);}Console.WriteLine("\n--- eCommerce Businesses ---");foreach (var e in context.Businesses.OfType<eCommerce>()){Console.WriteLine("{0} (#{1})", e.Name, e.LicenseNumber);Console.WriteLine("Online address is: {0}", e.URL);}Console.ReadKey();}}

  public abstract class Employee{public int EmployeeId { get; protected set; }public string FirstName { get; set; }public string LastName { get; set; }}public class FullTimeEmployee : Employee{public decimal? Salary { get; set; }}public class HourlyEmployee : Employee{public decimal? Wage { get; set; }}public class EmployeeContext: DbContext{public DbSet<Employee> Employees { get; set; }protected override void OnModelCreating(DbModelBuilder modelBuilder){base.OnModelCreating(modelBuilder);modelBuilder.Entity<Employee>().HasKey(e => e.EmployeeId).Property(e => e.EmployeeId).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);modelBuilder.Entity<Employee>().Map<FullTimeEmployee>(m => m.Requires("EmployeeType").HasValue(1)).Map<HourlyEmployee>(m => m.Requires("EmployeeType").HasValue(2));}

      private static void Main(string[] args){using (var context = new EmployeeContext()){var fte = new FullTimeEmployee{FirstName = "Jane",LastName = "Doe",Salary = 71500M};context.Employees.Add(fte);fte = new FullTimeEmployee{FirstName = "John",LastName = "Smith",Salary = 62500M};context.Employees.Add(fte);var hourly = new HourlyEmployee{FirstName = "Tom",LastName = "Jones",Wage = 8.75M};context.Employees.Add(hourly);context.SaveChanges();}using (var context = new EmployeeContext()){Console.WriteLine("--- All Employees ---");foreach (var emp in context.Employees){bool fullTime = !(emp is HourlyEmployee);Console.WriteLine("{0} {1} ({2})", emp.FirstName, emp.LastName,fullTime ? "Full Time" : "Hourly");}Console.WriteLine("--- Full Time ---");foreach (var fte in context.Employees.OfType<FullTimeEmployee>()){Console.WriteLine("{0} {1}", fte.FirstName, fte.LastName);}Console.WriteLine("--- Hourly ---");foreach (var hourly in context.Employees.OfType<HourlyEmployee>()){Console.WriteLine("{0} {1}", hourly.FirstName, hourly.LastName);}}Console.ReadKey();}

 protected override void OnModelCreating(DbModelBuilder modelBuilder){base.OnModelCreating(modelBuilder);modelBuilder.Entity<Employee>().HasKey(e => e.EmployeeId).Property(e => e.EmployeeId).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);modelBuilder.Entity<FullTimeEmployee>().Map(m =>{m.MapInheritedProperties();m.ToTable("FullTimeEmployee");});modelBuilder.Entity<HourlyEmployee>().Map(m =>{m.MapInheritedProperties();m.ToTable("HourlyEmployee");});}