private void Add_btn_Click_1(object sender, EventArgs e)
        {
            StudentFunction stuf   = new StudentFunction();
            int             id     = Convert.ToInt32(Id_txt.Text);
            string          fname  = FirstName_txt.Text;
            string          lname  = LastName_txt.Text;
            DateTime        bdate  = dateTimePicker1.Value;
            string          phone  = Phone_txt.Text;
            string          adrs   = Address_txt.Text;
            string          gender = "Male";

            if (Gender2.Checked)
            {
                gender = "Female";
            }
            MemoryStream picture   = new MemoryStream();
            int          born_year = dateTimePicker1.Value.Year;
            int          this_year = DateTime.Now.Year;

            if (((this_year - born_year) < 10 || (this_year - born_year) > 100))
            {
                MessageBox.Show("The student age must between 10 and 100 years old", "Invalid Birth Date", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            else if (Verify())
            {
                pictureBox1.Image.Save(picture, pictureBox1.Image.RawFormat);
                if (stuf.insertStudent(id, fname, lname, bdate, gender, phone, adrs, picture))
                {
                    MessageBox.Show("New student added successfully!", "Add student", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
                else
                {
                    MessageBox.Show("Error!", "Add student", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            else
            {
                MessageBox.Show("Empty fields", "Add student", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
            }
        }