private void btnSave_Click(object sender, EventArgs e)
{
cmd.CommandText = "insert into Student values('" + textBox1.Text + "','" + textBox2.Text + "','" + textBox3.Text + "','" + textBox4.Text + "','" + textBox5.Text + "','" + textBox6.Text + "','" + textBox7.Text + "','" + textBox8.Text + "','" + textBox9.Text + "','" + textBox10.Text + "','" + textBox11.Text + "','" + textBox12.Text + "','" + textBox13.Text + "','" + textBox14.Text + "','" + textBox15.Text + "','" + textBox16.Text + "','" + textBox17.Text + "','" + textBox18.Text + "','" + textBox19.Text + "','" + listBox1.SelectedItem + "','" + comboBox1.SelectedItem.ToString() + "','" + comboBox2.SelectedItem.ToString() + "','" + comboBox3.SelectedItem.ToString() + "','" + textBox20.Text + "','" + comboBox4.SelectedItem.ToString() + "','" + checkBox5.Text + "','" + textBox21.Text + "','" + textBox22.Text + "','" + textBox23.Text + "'," + int.Parse(textBox24.Text) + "," + int.Parse(textBox25.Text) + ",'" + checkBox3.Text + "','" + comboBox5.SelectedItem.ToString() + "','" + textBox26.Text + "','" + comboBox6.SelectedItem.ToString() + "','" + textBox27.Text + "','" + checkBox4.Text + "'," + int.Parse(textBox28.Text) + "," + int.Parse(textBox29.Text) + ",'" + checkBox1.Text + "','" + checkBox2.Text + "','" + listBox2.SelectedItem + "')";
cmd.Connection = con;
cmd.ExecuteNonQuery();
clear();