The following post shows how to write different types of joins in LINQ to SQL. I am using the Northwind database and LINQ to SQL for these examples.
1: NorthwindDataContext dataContext = new NorthwindDataContext();
INNER JOIN :
1: var q1 = from c in dataContext.Customers
2: join o in dataContext.Orders on c.CustomerID equals o.CustomerID
3: select new
4: {
5: c.CustomerID,
6: c.ContactName,
7: o.OrderID,
8: o.OrderDate
9: };
LEFT JOIN :
1: var q2 = from c in dataContext.Customers
2: join o in dataContext.Orders on c.CustomerID equals o.CustomerID into g
3: from a in g.DefaultIfEmpty()
4: select new
5: {
6: c.CustomerID,
7: c.ContactName,
8: a.OrderID,
9: a.OrderDate
10: };
INNER JOIN ON MULTIPLE :
1: var q3 = from c in dataContext.Customers
2: join o in dataContext.Orders on new { a = c.CustomerID, b = c.Country } equals new { a = o.CustomerID, b = "USA" }
3: select new
4: {
5: c.CustomerID,
6: c.ContactName,
7: o.OrderID,
8: o.OrderDate
9: };
INNER JOIN ON MULTIPLE WITH “OR” :
1: var q4 = from c in dataContext.Customers
2: from o in dataContext.Orders.Where(a => a.CustomerID == c.CustomerID || c.Country == "INDIA")
3: select new
4: {
5: c.CustomerID,
6: c.ContactName,
7: o.OrderID,
8: o.OrderDate
9: };
LEFT JOIN ON MULTIPLE WITH “OR” :
1: var q5 = from c in dataContext.Customers
2: from o in dataContext.Orders.Where(a => a.CustomerID == c.CustomerID || c.Country == "USA").DefaultIfEmpty()
3: select new
4: {
5: c.CustomerID,
6: c.ContactName,
7: o.OrderID,
8: o.OrderDate
9: };
More Example base on this article will post shortly 
