<asp:DataList ID="list" runat="server" CssClass="CategoryListContent" RepeatColumns="8" RepeatLayout="Flow">
  <ItemTemplate>
    <asp:HyperLink 
      ID="HyperLink1" 
      Runat="server" 
      NavigateUrl='<%# "../Catalog.aspx?DepartmentID=" + Request.QueryString["DepartmentID"] + "&CategoryID=" + Eval("CategoryID")  %>'
      Text='<%# Eval("Name") %>' 
      ToolTip='<%# Eval("Description") %>' 
      CssClass='<%# Eval("CategoryID").ToString() == Request.QueryString["CategoryID"] ? "CategorySelected" : "CategoryUnselected" %>'>>
    </asp:HyperLink>
  </ItemTemplate>
    <SeparatorTemplate>
        &nbsp;|&nbsp;
    </SeparatorTemplate>
    <ItemStyle HorizontalAlign="Center" VerticalAlign="Middle" />
    <SeparatorStyle HorizontalAlign="Center" VerticalAlign="Middle" />
</asp:DataList>

public partial class CategoriesList : System.Web.UI.UserControl
{
    protected void Page_Load(object sender, EventArgs e)
    {
        // don't reload data during postbacks
        if (!IsPostBack)
        {
            // Obtain the ID of the selected department
            string departmentId = Request.QueryString["DepartmentID"];
            // Continue only if DepartmentID exists in the query string
            if (departmentId != null)
            {
                // Catalog.GetCategoriesInDepartment returns a DataTable object containing
                // category data, which is displayed by the DataList
                list.DataSource = CatalogAccess.GetCategoriesInDepartment(departmentId);
                // Needed to bind the data bound controls to the data source
                list.DataBind();
            }
        }
    }
}

 // retrieve the list of categories in a department
  public static DataTable GetCategoriesInDepartment(string departmentId)
  {
    // get a configured DbCommand object
    DbCommand comm = GenericDataAccess.CreateCommand();
    // set the stored procedure name
    comm.CommandText = "GetCategoriesInDepartment";
    // create a new parameter
    DbParameter param = comm.CreateParameter();
    param.ParameterName = "@DepartmentID";
    param.Value = departmentId;
    param.DbType = DbType.Int32;
    comm.Parameters.Add(param);
    // create a new parameter
    param = comm.CreateParameter();
    param.ParameterName = "@PrivateEntry";
    param.Value = "false";
    param.DbType = DbType.String;
    comm.Parameters.Add(param);
    // execute the stored procedure
    return GenericDataAccess.ExecuteSelectCommand(comm);
  }