使用Entity Framework时遇到的问题

1、运行程序时提示 ，vension does not match. 差不多是这样一个提示，具体怎么样的给忘记了。

#1remove 'entity framework' from reference

#2update the app.config to 6.0.0

#3use Nuget to install Entity Framework: install-package entityframework

sometimes ,the Nuget prompts :the project has already installed entity framework.

　　now you shoud go to package.config to remove the entity framework tag

　　then you should repeat #3

2 使用entity framework的情况下，运行程序，提示 cannot load sql.data.sqlClient

you should go the class that extend the DBContext,to add a static constructor, as below

static myDBContext()

{

　　var _ = typeof(System.Data.Entity.SqlServer.SqlProviderServices);
　　var __ = typeof(System.Data.Entity.SqlServerCompact.SqlCeProviderServices); // I comment out this line ,because cannot find namespace SqlServerCompact

}

补充一点 ，entity framework 会自动在config文件里添加一个配置

<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
  <providers>

<provider ...............“sql.data.sqlClient”......./> //差不多是这个样子的

<providers>
</entityFramework>

去掉providers节点。

3 找不到命名空间System.Data.Objects

需要引用System.Data.Entiy