DropDownList duplicate items
<p>Hi I am trying to rebind data to a <code>DataList</code> that get's it's data from an <code>SqlDataSource</code> but I keep getting duplicate items. Here is my code:</p>

<p>
    
</p>

<pre><code>&lt;asp:SqlDataSource ID="CategoryDataSource" runat="server" 
    ConnectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\ASPNETDB.MDF;Integrated Security=True;User Instance=True" 
    ProviderName="System.Data.SqlClient" SelectCommand="SELECT [CategoryName] FROM [forum_categories]"&gt;
&lt;/asp:SqlDataSource&gt;

protected void Button6_Click( object sender , EventArgs e )
{
    string categoryToCreate = CreateCategory.Text;

    if(categoryToCreate != string.Empty)
    {
        CategoryCreateName.Visible = false;
        DataAccess.insertDataItem(categoryToCreate);
        CategoryList.DataBind(); 
    }
    else
    {
        CategoryCreateName.Visible = true;
    }
}
</code></pre>

<p>The <em>insertDataItem</em> inserts a new category into the database.</p>

<p>How can I update the items in the <code>DropDownList</code> so that I do not get duplicate items?</p>
