I am using Entity Framework Code First approach with AutomaticMigrationsEnabled = true:
Database.SetInitializer(new MigrateDatabaseToLatestVersi
If you have change in your entities, you need first run add-migration to create the migration script.
After that in your Global.asax
you need to have some code like this
var configuration = new MyProject.Configuration();
var migrator = new System.Data.Entity.Migrations.DbMigrator(configuration);
migrator.Update();
every time that you run your asp.net project it'll check if you have a new migration to run and run update-database automatically for you.