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技术 2022年11月17日
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本文介绍两个概念,防数据库自动删除,这是由于在code first模式下,当数据实体发生变化时,会对原来数据库进行删除,并将新数据表添加进来,但这对于我们的运营环境数据库,是万万不能接受的,第二个问题是数据迁移问题,当你有新的实体建立后,如何响应到数据库,这成为一个问题,当然实现也很简单,我们直接使用migrations工具即可.

一 防数据库删除

将你的业务DbInitializer的基类改成CreateDatabaseIfNotExists即可解决这个问题,这是在数据初始化时需要做的事,一般地,我们会选择当实体有变化时,自动更新数据库,但这样做影响比较大,所以我们不提倡使用.

  public class ManagerInitializer : CreateDatabaseIfNotExists<ManagerContext>
{
protected override void Seed(ManagerContext context)
{
    //初始化代码
}
}

二 数据迁移

这个问题也是必须要解决的,我们的实体添加后,数据库并没有对应的表,我们就需要使用migrations命令来对数据库进行更新,具体操作如下

1 开启migrations功能

enable-migrations -force

2 添加迁移版本

add-migration 名称后缀

我们每次修改实体后,都应该使用这个add-migration来升级历史版本

3 更新数据库

update-database

4 程序运行成功后,如图

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” alt=”” />

这时你查看自己的数据库,新加的实体已经自动添加到数据库了,呵呵.

aaarticlea/png;base64,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” alt=”” />

值得注意的是,通过这种方法进行数据库迁移,数据库的原数据是不会丢失的,即使你在原来的表上添加字段,老数据也不会丢,新字段会有默认值.

对于EF7来说,它只支持Code First模式,所以这种模式在dotnet框架里将会成为主流!

补充:

最近有朋友问我在服务器上如何进行数据的更新,即在生产环境如何使用迁移,可以读一下我的这篇文章<EF架构~CodeFirst生产环境的Migrations>

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