DL(DAL)

STEP 1: Create a class file like QuickLinksDL.cs


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using VCSB.INTRANET.BLL;
using Microsoft.SharePoint;

namespace VCSB.INTRANET.DAL
{
   public class QuickLinksDL
    {
       public static bool update(QuickLinksBL quickLinksBL)
       {

           bool update = false;
           SPSecurity.RunWithElevatedPrivileges(delegate()
           {
               using (VCSBINTRANETDataContext datacontxt = new VCSBINTRANETDataContext(SiteHelper.SiteUrl))
               {


                   var itemUpdate = (from updateequery in datacontxt.QuickLinks
                                     where updateequery.Id == Convert.ToInt32(quickLinksBL.ID)
                                     select updateequery).First();

                   itemUpdate.Title = quickLinksBL.Quicktitle;
                   itemUpdate.Url = quickLinksBL.Quickurl;
                   datacontxt.SubmitChanges();
               }
               update = true;
           });

           return update;
       }
       public static System.Data.DataTable GetAllListItem(QuickLinksBL quickLinksBL)
       {
           DataTable dt = new DataTable();
           dt.Columns.Add("ID");
           dt.Columns.Add("Title");
           dt.Columns.Add("Url");

           DataRow row;
           SPSecurity.RunWithElevatedPrivileges(delegate()
           {
               using (VCSBINTRANETDataContext context = new VCSBINTRANETDataContext(SiteHelper.SiteUrl))
               {
                   var quer = from quicklinksData in context.QuickLinks
                              orderby quicklinksData.Id descending
                              select quicklinksData;

                   if (quer != null)
                   {
                       foreach (QuickLinksItem item in quer)
                       {
                           row = dt.Rows.Add();
                           row["ID"] = Convert.ToString(item.Id);
                           row["Title"] = Convert.ToString(item.Title);
                           row["Url"] = Convert.ToString(item.Url);
                       }
                   }
               }
           });
           return dt;
       }
       public static System.Data.DataTable GetSingleRowListItem(QuickLinksBL quickLinksBL)
       {

           DataTable dt = new DataTable();
           dt.Columns.Add("ID");
           dt.Columns.Add("Title");
           dt.Columns.Add("Url");
           DataRow row;
           SPSecurity.RunWithElevatedPrivileges(delegate()
           {
               using (VCSBINTRANETDataContext context = new VCSBINTRANETDataContext(SiteHelper.SiteUrl))
               {
                   var quer = from quicklinksData in context.QuickLinks
                              where quicklinksData.Id == quickLinksBL.ID
                              select quicklinksData;

                   if (quer != null)
                   {
                       foreach (QuickLinksItem item in quer)
                       {
                           row = dt.NewRow();
                           row["ID"] = Convert.ToString(item.Id);
                           row["Title"] = Convert.ToString(item.Title);
                           row["Url"] = Convert.ToString(item.Url);
                           dt.Rows.Add(row);

                       }
                   }
               }
           });
           return dt;
       }
    }
}