This is partly true. Migrations are still required once you have your app in production, because you have to tell the DB how to change itself in a way that preserves information.
只是部分情况下不需要迁移，一旦你需要将你的程序投入生产应用中去，那么迁移是仍然需要的，因为你已经告诉DB如何修改以保存信息。
The chemical structure and production cost of vat black BBN and vat black DB are analyzed. The process conditions of yarn dyeing with these two dyes are introduced as well as the attentions in dyeing.
分析了还原黑BBN和还原黑DB的结构特点和生产成本，具体介绍了纱线染色的工艺条件，以及染色过程中需注意的事项。
应用推荐