title: Add more columns to GridView
body: <p>I have a <code>GridView</code>, which is bound to a database table.  This <code>GridView</code> shows the some books (price, author information, etc).</p>
  
  <p>I wants to add a column "<em>Add to Cart</em>" to this <code>GridView</code> at the end of each book.  I added one column with text "Add to cart".  But, on debug, it shows an error as "<em>Add to cart</em> is not present in db."</p>
  
  <p>So please tell me how to append this column to the <code>GridView</code>.</p>
  
  <p><strong>Markup</strong></p>
  
  <pre><code>&lt;asp:GridView ID="GridView1" runat="server" BorderStyle="Double" 
      BorderWidth="3px" CellPadding="4" GridLines="Horizontal" Height="260px" 
      Width="661px"&gt;
  
      &lt;FooterStyle BackColor="White" ForeColor="#333333" /&gt;
      &lt;HeaderStyle BackColor="#336666" Font-Bold="True" ForeColor="White" /&gt;
      &lt;PagerStyle BackColor="#336666" ForeColor="White" HorizontalAlign="Center" /&gt;
      &lt;RowStyle BackColor="White" ForeColor="#333333" /&gt;
      &lt;SelectedRowStyle BackColor="#339966" Font-Bold="True" ForeColor="White" /&gt;
      &lt;SortedAscendingCellStyle BackColor="#F7F7F7" /&gt;
      &lt;SortedAscendingHeaderStyle BackColor="#487575" /&gt;
      &lt;SortedDescendingCellStyle BackColor="#E5E5E5" /&gt;
      &lt;SortedDescendingHeaderStyle BackColor="#275353" /&gt;
      &lt;Columns&gt;
          &lt;asp:ButtonField Text="Add To Cart"&gt;
          &lt;FooterStyle HorizontalAlign="Right" /&gt;
          &lt;HeaderStyle HorizontalAlign="Right" /&gt;
          &lt;ItemStyle HorizontalAlign="Left" /&gt;
          &lt;/asp:ButtonField&gt;
      &lt;/Columns&gt;
  &lt;/asp:GridView&gt;
  </code></pre>
  
  <p><strong>Code</strong></p>
  
  <pre><code>public partial class WebForm9 : System.Web.UI.Page&lt;p&gt;
  {
      buybl obj = new buybl();
      protected void Page_Load(object sender, EventArgs e)
      {
          obj.dept = "IT";
          GridView1.DataSource = obj.select();
          GridView1.DataBind();
      }
  }
  </code></pre>