SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\veritabani.mdf;Integrated Security=True;User Instance=True");

            string sqlIns = "INSERT INTO liste (adi_soyadi, telefon, tedavi, durum, tarih, saat, odenen, tutar) VALUES (@adi_soyadi, @telefon, @tedavi, @durum, @tarih, @saat, @odenen, @tutar)";

            SqlCommand com = new SqlCommand(sqlIns, con);

            com.Parameters.Add("@adi_soyadi", textBox1.Text);
            com.Parameters.Add("@telefon", maskedTextBox1.Text);
            com.Parameters.Add("@tedavi", textBox3.Text);
            com.Parameters.Add("@durum", comboBox1.Text);
            com.Parameters.Add("@tarih", Convert.ToDateTime(dateTimePicker2.Text));
            com.Parameters.Add("@saat", dateTimePicker1.Text);
            com.Parameters.Add("@odenen", textBox4.Text);
            com.Parameters.Add("@tutar", textBox7.Text);

                con.Open();
                com.ExecuteNonQuery();
                con.Close();

                MessageBox.Show("Randevu Eklendi!");
                this.Close();