/// <summary>
        /// clear all controls and change text in the update button when user click add button
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnAdd_Click(object sender, EventArgs e)
        {
            try
            {
                ((mdiForm)this.MdiParent).StatusStipLabel.Text = "Adding a new record";
                ((mdiForm)this.MdiParent).StatusStipLabe2.Text = "";
                cmbBook.SelectedIndex   = 0;
                cmbAuthor.SelectedIndex = 0;

                LoadCategory();

                btnUpdate.Text    = "Create";
                btnAdd.Enabled    = false;
                btnDelete.Enabled = false;
                createNewRecord   = true;

                NavigationState(false);
                UT.ClearControls(grpBook.Controls);
                UT.ClearControls(grpAuthor.Controls);
            }

            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, ex.GetType().ToString());
            }
        }
        /// <summary>
        /// clear all controls and change text in the update button when user click add button
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnAdd_Click(object sender, EventArgs e)
        {
            try
            {
                ((mdiForm)this.MdiParent).StatusStipLabel.Text = "Adding a new author";
                ((mdiForm)this.MdiParent).StatusStipLabe2.Text = "";
                UT.ClearControls(grpAuthorInfo.Controls);
                UT.ClearControls(grpCareer.Controls);
                UT.ClearControls(grpPublishedWork.Controls);

                rdoMale.Checked = true;

                LoadCategory();

                btnUpdate.Text    = "Create";
                btnAdd.Enabled    = false;
                btnDelete.Enabled = false;
                createNewRecord   = true;

                NavigationState(false);

                grpPublishedWork.Enabled = false;
            }

            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, ex.GetType().ToString());
            }
        }