.net core 启用MARS(多个活动结果集)

在开发时候遇到错误

There is already an open DataReader associated with this Command which must be closed first.

解决：如果是用的sql server 数据库，可以启用多个活动结果集（MARS）,是与sql server 一起使用的功能，允许在单个连接上执行多个批处理，启用MARS时候每个命令对象都将一个会话添加到连接中，

启用也方便将 MultipleActiveResultSets=True 添加到连接字符串中

  "ConnectionStrings": { "con": "server=.;database=bbs;uid=sa;pwd=mima;MultipleActiveResultSets=True" },

 

There is already an open DataReader associated with this Command which must be closed first.