DL(DAL)

STEP 1: Create a class file like AppsDL.cs


namespace VCSB.INTRANET.DAL
{
    public class AppsDL
    {
        public static  void GetAppsListItem(DataList Apps)
        {
            SPSite spsite = SPContext.Current.Site;
            SPWeb spweb = spsite.OpenWeb();
            SPList spList = spweb.Lists["AppsCategory"];
            SPList spList1 = spweb.Lists["Apps"];
            SPListItemCollection spListItems = spList.Items;
            SPListItemCollection spListItems1 = spList1.Items;

            var query1 = from SPListItem pi in spList.Items
                         select pi;
            DataTable dd1 = new DataTable();
            dd1.Columns.Add("Title");
            DataRow row;
            foreach (var grp in query1)
            {
                row = dd1.Rows.Add();
                row["Title"] = Convert.ToString(grp.Title);
            }
            Apps.DataSource = dd1;
            Apps.DataBind();

            var query = from SPListItem pi in spList.Items
                        from SPListItem ci in spList1.Items
                        where pi.Title.ToString().Equals(new SPFieldLookupValue(ci["Category"].ToString()).LookupValue)
                        select new { Parent = pi, Child = ci };

            DataTable ds1 = new DataTable();
            ds1.Columns.Add("Title");
            ds1.Columns.Add("Category");
            ds1.Columns.Add("AppsUrl");
            DataRow row1;
            foreach (var grp1 in query)
            {
                row1 = ds1.Rows.Add();
                row1["Title"] = Convert.ToString(grp1.Parent.Title);
                row1["Category"] = Convert.ToString(grp1.Child.Title);
                row1["AppsUrl"] = Convert.ToString(grp1.Child["AppsURL"]);

            }


            DataSet test = new DataSet();
            test.Tables.Add(ds1);

            foreach (DataListItem item in Apps.Items)
            {
                string dataTitle = Convert.ToString(Apps.DataKeys[item.ItemIndex]);
                DataList gvr = (DataList)Apps.Items[item.ItemIndex].FindControl("Appscat");
                DataTable dt = new DataTable();
                dt.Columns.Add("Category");
                dt.Columns.Add("AppsUrl");
                foreach (DataRow item1 in test.Tables[0].Rows)
                {
                    DataRow drr = dt.NewRow();
                    if (Convert.ToString(item1["Title"]) == dataTitle)
                    {
                        drr["Category"] = item1["Category"].ToString();
                        drr["AppsUrl"] = Convert.ToString(item1["AppsUrl"]);
                        dt.Rows.Add(drr);
                    }
                }
                gvr.DataSource = dt;
                gvr.DataBind();
            }
           
        }

    }
}