Linq to SharePoint List. (Where , Join )

This article give you information regarding how to use Liinq with SharePoint List to fetch data from SPList.

For Example there are three SharePoint List . Customers , Orders , OrderDetails. (Please See image below). In Orders list CustomerID is lookup field and in OrderDetails list OrderID is lookup field.

Now Get All Customer From Customer List using Linq.

SPSite site = new SPSite("http://localhost:45833"); 
SPWeb web = site.OpenWeb();
SPList lstCustomer = web.Lists["Customers"];

var customers = from SPListItem customer in lstCustomer.Items
                       select customer;

by use of SPListItem (As we use select customer in Linq query)
foreach (SPListItem item in customers)
{
Console.WriteLine(item.ID.ToString() + "-" +item["CustomerName"].ToString());
}

or by using ananymous type

var customers = from SPListItem customer in lstCustomer.Items
                       select new {ID = customer.ID.ToString(), Name= customer[“CustomerName”].ToString()};
foreach (var item in customers)
{
Console.WriteLine(item.ID + "-" + item.Name);
}

use of where clause with this

var customers = from SPListItem customer in lstCustomer.Items
                       where customer.ID == 1
                       select new { ID = customer.ID.ToString(), Name = customer["CustomerName"].ToString() };

Join Three List to get Related Data

SPList lstCustomer = web.Lists["Customers"];
SPList lstorders = web.Lists["Orders"];
SPList lstorderdetails = web.Lists["OrderDetails"];
var customerorders =

from SPListItem customer in lstCustomer.Items
join SPListItem order in lstorders.Items on customer.ID.ToString() equals order["CustomerID"].ToString().Split(new string[]{";#"},StringSplitOptions.None)[0]
join SPListItem orderdetail in lstorderdetails.Items on order.ID.ToString() equals orderdetail["OrderID"].ToString().Split(new string[] { ";#" }, StringSplitOptions.None)[0]                                
select new {Product = orderdetail["Product"].ToString() , Price = Convert.ToDouble(orderdetail["Price"].ToString()) , Qty = Convert.ToInt32(orderdetail["Qty"].ToString()) , OrderID = order.ID , OrderDate = order["OrderDate"].ToString() , CustomerID = customer.ID.ToString(), CustomerName = customer["CustomerName"].ToString() };

foreach (var item in customerorders)
               {
                   Console.WriteLine(item.Product + "  " + item.Price.ToString() + "," + item.Qty.ToString() + ","+ (item.Price * item.Qty).ToString() + ","+ item.OrderID.ToString() + "," + item.OrderDate + "," + item.CustomerName);
               }

                  Note :In above code, I used split operation on string in order to compare LookUp Field ID Value with ID of parent List. There is also posibility to join more than three tables.

For that you have to use nested this join inside other. Please give your comment or advice on this.