In this system, using two-level associationkey management technology realizes key management of storage grouping algorithm.
在数字防伪系统中，采用“二级关联密钥管理技术”来实现存储分组算法的密钥管理。
2
For one-to-one associations, developers have to select which end of the association holds the foreign key that represents the other end (this gets propagated down to the database schema).
对于一对一关联，开发者必须选择关联的哪一端持有代表另一端的外键(这会向下传给数据库模式)。
3
When we are able to relate without ambiguity any association end to a foreign key, we can apply the correspondence to specify to which primary key the foreign key refers.