protected void Button1_Click(object sender, EventArgs e)
{
switch (DropDownList1.SelectedValue)
{
case "1":
GridView2.DataSource = admin.bookAll();
GridView2.DataBind();
break;
case "2":
GridView2.DataSource = admin.bookNameSel(TextBox12.Text);
GridView2.DataBind();
break;
case "3":
GridView2.DataSource = admin.bookISBNSel(TextBox12.Text);
GridView2.DataBind();
break;
case "4":
GridView2.DataSource = admin.bookAmountSel(Convert.ToInt32(TextBox12.Text));
GridView2.DataBind();
break;
}
}