DbProviderFactories.GetFactory 获取mysql不成功， 添加配置文件
<system.data>
<DbProviderFactories >
<add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data" />
</DbProviderFactories>
</system.data>