无法生成模型，因为存在以下异常：‘System.Data.StrongTypingException：表‘TableDetails‘中的列‘IsPrimaryKey‘的值为DBNull。---> System.InvalidCastException：指定的转换无效。

原文链接http://stackoverflow.com/questions/33575109/mysql-entity-the-value-for-column-isprimarykey-in-table-tabledetails-is

 原文：

Entity Framework (version 6.1.3) and MySQL Server (>= 5.7.6)

One way to resolve the issue is,

1. Open Services (services.msc) and restart MySQL57 service.   
2. Execute the following commands in MySQL.
   use <<database name>>;
   set global optimizer_switch=‘derived_merge=OFF‘;
3. Update the .edmx.

It‘s a late reply. But hope it will help somebody.

Thanks.

 大致翻译：

1.重新启动mysql服务

2.打开命令列界面

set global optimizer_switch=‘derived_merge=OFF‘;

3.重新新建EF

EF连接Mysql 表'TableDetails'中的列'IsPrimaryKey'的值为DBNull