private void btnRandevuOnay_Click(object sender, EventArgs e)
        {
            DateTime      tarih            = dateTimePicker1.Value.Date;
            string        sqlFormattedDate = tarih.Date.ToString("yyyy-MM-dd");
            SqlConnection con = new SqlConnection(conString);

            try
            {
                con.Open();
                SqlCommand cmd = new SqlCommand("select * from randevular where tarih=@tarih and saat=@saat", con);
                cmd.Parameters.AddWithValue("@tarih", sqlFormattedDate);
                cmd.Parameters.AddWithValue("@saat", comboBoxSaat.Text);
                cmd.ExecuteNonQuery();

                SqlDataAdapter da = new SqlDataAdapter();
                da.SelectCommand = cmd;
                DataSet ds = new DataSet();
                da.Fill(ds);
                int count = ds.Tables[0].Rows.Count;
                if (count == 1)
                {
                    MessageBox.Show("Seçilen randevu daha önce alınmış. Yeni bir randevu alınız..");
                    Form f = new hastaPanel(textBoxTCKimlikNo.Text);
                    f.Show();
                    Close();
                }
                else
                {
                    randevuKaydi();
                }
                con.Close();
            }catch (Exception ex) {
                Console.WriteLine(ex.Message);
            }
        }
        private void hastaGirisi()
        {
            string girilenTC    = textBoxHastaGiris1.Text;
            string girilensifre = textBoxHastaGiris2.Text;

            int count = 0;

            SqlConnection con = new SqlConnection(conString);

            try
            {
                con.Open();
                string query = "SELECT * FROM hastaGiris WHERE TCKimlikNo = '" + girilenTC.Trim() + "' AND sifre = '" + girilensifre.Trim() + "'";

                SqlDataAdapter sda = new SqlDataAdapter(query, con);
                DataSet        ds  = new DataSet();
                sda.Fill(ds);
                count = ds.Tables[0].Rows.Count;

                con.Close();


                if (count == 1)
                {
                    Form form = new hastaPanel(textBoxHastaGiris1.Text);

                    form.Show();
                    Hide();
                }
                if (count != 1)
                {
                    MessageBox.Show("TC kimlik no veya şifre hatalı!!");
                }
            }


            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }