你不能拥有多对多（这是你创建
- 你所描述的）。

You cannot have that with the many-to-many (it's what you're creating - and what you described).

当您删除公司/联系人时，连接表记录将被删除。

When you delete company / contact - the 'join' table records get deleted.

您可以简化此操作，只需在配置中执行此操作（删除所有内容）：

You can simplify that and just do this in your config (remove all you have):

modelBuilder.Entity<Company>()
    .HasMany(c => c.Address)
    .WithOptional()
    .WillCascadeOnDelete(true);

modelBuilder.Entity<Contact>()
    .HasMany(c => c.Address)
    .WithOptional()
    .WillCascadeOnDelete(true);