C# 获取App.config里的连接字符串
1.添加引用
2.添加命名空间
3.查看App.config连接字符串的名字
4.拿到连接字符串
string str = ConfigurationManager.ConnectionStrings["ConnectSQL.Properties.Settings.StudentsConnectionString"].ConnectionString;
string str = ConfigurationManager.ConnectionStrings["ConnectSQL.Properties.Settings.StudentsConnectionString"].ConnectionString;