string connetStr = ConfigurationManager.ConnectionStrings["connStr"].ConnectionString;

MySqlConnection conn = new MySqlConnection(connetStr);

try
{
   conn.Open();//打开通道，建立连接，可能出现异常,使用try catch语句
   Console.WriteLine("已经建立连接");
   //在这里使用代码对数据库进行增删查改
}
catch (MySqlException ex)
{
   Console.WriteLine(ex.Message);
   switch (ex.Number)
   {
      case 0:
        Console.WriteLine("Cannot connect to server.  Contact administrator");
        break;
      case 1045:
        Console.WriteLine("Invalid username/password, please try again");
        break;
   }
}
finally
{
   Console.WriteLine("关闭数据库");
   conn.Close();
}