With this strategy, you can move up or down to any logical database schema state.
用这个策略，可以前后转移到逻辑数据库模式的任何状态。
Holding data attributes in XML could allow a very flexible schema in which attributes can be removed or added without changing the logical database schema.
将数据属性保存在XML中可以允许采用非常灵活的模式，能在不用更改逻辑数据库模式的情况下添加或删除属性。
Some database changes require changes in data as well as schema, and some of those data changes require logical changes.
有些数据库变化要求数据和模式一起变化，有些数据变化要求逻辑变化。
Slice does not require such additional schema-level information because it maintains the association between a persistence instance and its original database partition via its logical name.
Slice不需要这类额外的模式层的信息，因为它根据持久性实例的逻辑名维护了实例和其原始数据库分区间的关联。
By utilizing Rails migration and defining your database schema changes in Ruby files, versioning of changes takes place in a logical manner.
通过利用Rails迁移和在Ruby文件中定义数据库模式更改，可以以逻辑的方式对更改进行版本控制。
By utilizing Rails migration and defining your database schema changes in Ruby files, versioning of changes takes place in a logical manner.
通过利用Rails迁移和在Ruby文件中定义数据库模式更改，可以以逻辑的方式对更改进行版本控制。
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