How CodeFirst default LazyloadingEnable is true ?

Yes, using Include also we can retrive the relavent data using Navigation Property,but which excepts a navigation property. like

   public class Employee

    {

        [Key]

        public int Eid { get; set; }

        public string Ename { get; set; }

        public string EPhone { get; set; }

        public int EmpDept { get; set; }     

        public virtual Departments   Dept { get; set; }  // Navigation Property

    }

    public class Departments

    {

        [Key]

        public int Did { get; set; }

        public string DName { get; set; }   

    }

    public class Conn : DbContext

    {

        public DbSet<Employee> emps { get; set; }

        public DbSet<Departments> depts { get; set; }    

        protected override void OnModelCreating(DbModelBuilder modelBuilder)

        {

            modelBuilder.Entity<Employee>()

               .HasRequired(a => a.Dept)

               .WithMany()

               .HasForeignKey(u => u.EmpDept);

            base.OnModelCreating(modelBuilder);

        }

   

    }

then

-----

class Program

    {

        static void Main(string[] args)

        {

        Conn context = new Conn();

         Employee eobj = new Employee { Ename = "France", EPhone = "7176", EmpDept = 2 };

            context.emps.Add(eobj);

            context.SaveChanges();

        }

   }

thin Executed in DAtabase

Eid          Ename        EPhone                EmpDept             Did         DName

1              raju            7171                          1              1              Accounts

2              naveen        7172       2              2              Business

3              Chaitanya     7173          1              1              Accounts

4              Dinesh       7174       2              2              Business

5              Eswar     7175       3                3              DBA

6              France      7176       2                2              Business

  IQueryable<Employee> 

t = context.emps.Include("Dept").Where(n => n.Ename == "raju").Select(n => n);

immediate window

t

SELECT 

[Extent1].[Eid] AS [Eid], 

[Extent1].[Ename] AS [Ename], 

[Extent1].[EPhone] AS [EPhone], 

[Extent1].[EmpDept] AS [EmpDept], 

[Extent2].[Did] AS [Did], 

[Extent2].[DName] AS [DName]

FROM  [dbo].[Employees] AS [Extent1]

INNER JOIN [dbo].[Departments] AS [Extent2] ON [Extent1].[EmpDept] = [Extent2].[Did]

WHERE N'raju' = [Extent1].[Ename]

Eid Ename EPhone EmpDept Did DName

1 raju 7171 1 1 Accounts

6 raju 7176 2 2 Business

emps------------> select * from emp

here where is department details?
so by default lazyloading is enabled but as per quering the data base only which returns now.
which will generates.

as well as

    public class Departments

    {

        [Key]

        public int Did { get; set; }

        public string DName { get; set; }

        public virtual ICollection<Employee> DeptEmployees { get; set; }

    }

now we can insert multiple employee records
as well as
we can retrive multiple employee records also. as a collections

how to insert multiple records:

   Employee emp = new Employee { Ename = "narayanarao", EPhone = "7175" };

                Employee emp1=new Employee{ Ename="shekar", EPhone="7176"};

                List<Employee> elist=new List<Employee>();

                elist.Add(emp);

                elist.Add(emp1);

                Departments d = new Departments { DeptEmployees = elist, DName="Professionals" };

                context.depts.Add(d);

                context.SaveChanges();

how to retrive particular dept records :

  var t = context.depts.Include("DeptEmployees");           //     DeptEmployees 

                foreach (var item in t)

                {

          ICollection<Employee> ems = item.DeptEmployees;  // grouped by department id

                    foreach (var items in ems)

                    {

                        Console.WriteLine(items.Ename);

                        Console.WriteLine(item.DName);

                    }

                }

Note:   DeptEmployees  column is  created at Employee table why because to this column referenceing the apporiate Employee.

Columns:


EmpDept----particular employee

Departments_Did-----collection of employees/ a particular dept employees