what is model first approach in entity framework code example

Example 1: entity save example in c# model first

// disconnected new entity 
var student = new Student(){ StudentName = "Bill" };

using (var context = new SchoolDBEntities())
{
    context.Entry(student).State = student.StudentId == 0? EntityState.Added : EntityState.Modified;

    context.SaveChanges();
}

Example 2: entity save example in c# model first

exec sp_executesql N'INSERT [dbo].[Student]([StudentName], [StandardId])
VALUES (@0, NULL)
SELECT [StudentID] FROM [dbo].[Student]
WHERE @@ROWCOUNT > 0 AND [StudentID] = scope_identity(),@0='Bill'

Example 3: entity save example in c# model first

// disconnected existing entity 
var student = new Student(){ StudentId = 1, StudentName = "Steve" };

using (var context = new SchoolDBEntities())
{
    context.Entry(student).State = student.StudentId == 0? EntityState.Added : EntityState.Modified;

    context.SaveChanges();
}