Add or Remove Multiple Entities in Entity Framework:

Entity Framework 6 introduced methods to add and remove a collection of entities in one go. The DbSet.AddRange() method attaches a collection of entities to the context with Added state, which will execute the INSERT command in the database for all entities on SaveChanges(). In the same way, the DbSet.RemoveRange() method attaches a collection of entities with Deleted state, which in turn will execute the DELETE command for all entities on SaveChanges().

Adding or removing entities using the AddRange and RemoveRange methods improves the performance. It is recommended to use these methods if you want to insert or delete large number of records from the database using Entity Framework.

The following example demonstrates saving multiple entities.

IList<Student> newStudents = new List<Student>() {
                                    new Student() { StudentName = "Steve" };
                                    new Student() { StudentName = "Bill" };
                                    new Student() { StudentName = "James" };
                                };               

using (var context = new SchoolDBEntities())
{
    context.Students.AddRange(newStudents);
    context.SaveChanges();
}

The following example demonstrates removing multiple entities.

IList<Student> studentsToRemove = new List<Student>() {
                                    new Student() { StudentId = 1, StudentName = "Steve" };
                                    new Student() { StudentId = 2, StudentName = "Bill" };
                                    new Student() { StudentId = 3, StudentName = "James" };
                                };
    
using (var context = new SchoolDBEntities())
{
    context.Students.RemoveRange(studentsToRemove);
    context.SaveChanges();
}

Note: EF Core improves the performance of AddRange and RemoveRange methods by executing the INSERT and DELETE commands for all entities in a single database round trip.