App.config加入此代码
<connectionStrings>
<add name ="connStr" connectionString="server=.;uid=sa;pwd=sa;database=t_DB"/>
</connectionStrings>
DBHelper所在的层需要添加引用using System.Configuration;(三个的上边)
连接字符串写:
public static string connStr = ConfigurationManager.ConnectionStrings["connStr"].ConnectionString;