EF外键属性不可为空

Question

我有两个完全相同的数据库表，一个prod和一个dev。每当我部署到开发数据库时，一切工作正常。并且prod数据库允许将此错误与我试图使用EF & MVC将数据写回数据库。

System.InvalidOperationException: The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. When a change is made to a relationship, the related foreign-key property is set to a null value. If the foreign-key does not support null values, a new relationship must be defined, the foreign-key property must be assigned another non-null value, or the unrelated object must be deleted. 
    at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options) 
    at System.Data.Entity.Internal.InternalContext.SaveChanges() 

当然，我已经检查这个http://blogs.msdn.com/b/dsimmons/archive/2010/01/31/deleting-foreign-key-relationships-in-ef4.aspx

好像没有问题，我的EF代码，纯粹db表问题 无论如何，我可以找到更多的细节？

Answer 1

删除外键关系在EF4 在这个问题上 http://blogs.msdn.com/b/dsimmons/archive/2010/01/31/deleting-foreign-key-relationships-in-ef4.aspx