Get a data random from mysql using C#

Question

hello master

 a have a problem to get a data from mysql

i have a database like this

idquestion || question || optiona || optionb || optionc || optiond || answer

 

i try to get a random data from mysql to From in c#

 

this my code to get a data from mysql

 

private DataTable tquestion;
        public string ide = "";
        public string soale= "";
        public string ae="";
        public string be="";
        public string ce="";
        public string de="";
        public string je="";
        public string NISe;

public void getdata()
{
            ide = tquestion.Rows[0].ItemArray[0].ToString();
            soale = tquestion.Rows[0].ItemArray[1].ToString();
            ae = tquestion.Rows[0].ItemArray[1].ToString();
            be = tquestion.Rows[0].ItemArray[2].ToString();
            ce = tquestion.Rows[0].ItemArray[3].ToString();
            de = tquestion.Rows[0].ItemArray[4].ToString();
            sql = "SELECT * FROM question ORDER BY RAND() LIMIT 1";
            tquestion = koneksi.tampil_data(sql);
            textBox1.Text = soale;
            rbA.Text = ae;
            rbB.Text = be;
            rbC.Text = ce;
            rbD.Text = de;

}

this the erorr form c#

System.NullReferenceException was unhandled
  HResult=-2147467261
  Message=Object reference not set to an instance of an object.
  Source=sistem_basis_data
  StackTrace:
       at sistem_basis_data.home.ambilsoal() in c:\Users\Asus\Documents\client\sistem_basis_data24\sistem_basis_data\sistem_basis_data\home\home.cs:line 83
       at sistem_basis_data.home.home_Load(Object sender, EventArgs e) in c:\Users\Asus\Documents\client\sistem_basis_data24\sistem_basis_data\sistem_basis_data\home\home.cs:line 70
       at System.Windows.Forms.Form.OnLoad(EventArgs e)
       at System.Windows.Forms.Form.OnCreateControl()
       at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
       at System.Windows.Forms.Control.CreateControl()
       at System.Windows.Forms.Control.WmShowWindow(Message& m)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
       at System.Windows.Forms.Form.WmShowWindow(Message& m)
       at System.Windows.Forms.Form.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
  InnerException: