protected void Button_submit_Click(object sender, EventArgs e)
    {
        if (TextBox_sap.Text != "" && TextBox_name.Text != "" && DropDownList_branch.SelectedValue != "" &&
            DropDownList_year.SelectedValue != "" && DropDownList_course.SelectedValue != "" && DropDownList_gender.SelectedValue != "" &&
            TextBox_mobile_self.Text != "" && TextBox_mobile_parent.Text != "" &&
            TextBox_email.Text != "" && TextBox_address.Text != "" && DropDownList_mentor.SelectedValue != "")
        {
            if (Page.IsValid)
            {
                //encrypt sap_id here

                String password = Encrypt(TextBox_sap.Text.Trim());
                int    i        = Data_Access.Register_student(TextBox_sap.Text, TextBox_name.Text, password, DropDownList_branch.SelectedValue,
                                                               DropDownList_year.SelectedValue, DropDownList_course.SelectedValue, DropDownList_gender.SelectedValue, TextBox_mobile_self.Text, TextBox_mobile_parent.Text,
                                                               TextBox_email.Text, TextBox_address.Text, DropDownList_mentor.SelectedValue
                                                               );

                if (i == 2)
                {
                    Response.Write("Successful");
                }
                else if (i == 3)
                {
                    Response.Write("SAP ID already registered");
                }
                else
                {
                    Response.Write("Unsuccessful");
                }
            }
        }
        else
        {
            Response.Write("Enter all the fields");
        }
    }