When a type has either type or table dependents, altering a type definition becomes more complicated because existing persistent data relies on the current type definition.

• 如果一个对象类型被数据表或其他对象类型所依赖,那么修改此对象类型的定义将导致更为复杂的问题,因为已存在的持久化数据依赖于此对象类型的定义。