EF modifies table structure, does not delete data

1, Global.asax.cs Add the following code:database.setinitializer<efdbcontext> (NULL);
2, modify the table structure,
3. Modify the Entity class and table structure synchronization
4, if the first data migration executes the following code:

Enable-migrations-projectname Sportstore.domain-contexttypename SportStore.Domain.Entities.Concrete.EFDbContext

Add-migration-projectname Sportstore.domain Initial

Update-database-projectname Sportstore.domain

5, if not the first time, execute the code:

Enable-migrations-force-projectname Sportstore.domain-contexttypename SportStore.Domain.Entities.Concrete.EFDbContext
Add-migration-force-projectname Sportstore.domain Initial
Update-database–verbose-projectname Sportstore.domain

EF modifies table structure, does not delete data