C# Programming : Joining using LINQ in LINQ To Objects

LINQ also supports the joining of data from different collections using a familiar SQL-like join syntax.
Here are sample example of this.
In this example there is book class which has PublisherId field , this fields contains only numeric values.
If we need to display Publisher Name we have to join this book class object to Publishers class object which has Publisher Name of each Publisher Id key.
In this example we display book title from Books class and it's publisher name from publishers class.

C# Example :

    public class Books
    {
        public string Title { get; set; }
        public string ISBN { get; set; }
        public DateTime ReleaseDate { get; set; }
        public int Pages { get; set; }
        public int PublisherId { get; set; }
    }
    public class Publisher
    {
        public int PublisherId { get; set; }
        public string PublisherName { get; set; }
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        var bookslist = GetBooksList();
        var publisherslist=GetPublishers();
        var query = from bl in bookslist
                    join p in publisherslist on bl.PublisherId equals p.PublisherId
                    select new { bl.Title,p.PublisherName};
        this.gvBooks.DataSource = query;
        this.gvBooks.DataBind();
    }
    public List<Books> GetBooksList()
    {
        return new List<Books> {
                        new Books { Title="ASP.NET",ISBN="asp1",ReleaseDate= DateTime.Parse( "11/11/2010") ,Pages=200,PublisherId=1},
                        new Books { Title="C#.NET",ISBN="c#2",ReleaseDate= DateTime.Parse( "10/11/2010") ,Pages=500,PublisherId=1},
                        new Books { Title="VB.NET",ISBN="vb3",ReleaseDate= DateTime.Parse( "5/5/2009") ,Pages=400,PublisherId=1},
                        new Books { Title="SQL Server",ISBN="sql4",ReleaseDate= DateTime.Parse( "6/9/2010"),Pages=300,PublisherId=2 },
                        new Books { Title="JAVA",ISBN="java5",ReleaseDate= DateTime.Parse( "8/5/2011"),Pages=400,PublisherId=3 }
        
        };

    }
    public List<Publisher> GetPublishers()
    {
        return new List<Publisher> {
                        new Publisher { PublisherId=1, PublisherName="Microsoft" } ,
                        new Publisher { PublisherId=2, PublisherName="Wrox" } ,
                        new Publisher { PublisherId=3, PublisherName="Sun Publications" }
        };
    }

VB.net Example :

    Public Class Books
        Public Property Title() As String
        Public Property ISBN As String
        Public Property ReleaseDate As Date
        Public Property Pages As Integer
        Public Property PublisherId As Integer
    End Class
    Public Class Publisher
        Public Property PublisherId() As Integer
        Public Property PublisherName() As String
    End Class
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim bookslist = GetBooksList()
        Dim publisherslist = GetPublishers()
        Dim query = From bl In bookslist _
                    Join p In publisherslist On p.PublisherId Equals bl.PublisherId _
                    Select bl.Title, p.PublisherName
        gvBooks.DataSource = Query
        gvBooks.DataBind()
    End Sub
    Public Function GetBooksList() As List(Of Books)
        Dim lstBooks As New List(Of Books) From { _
                                New Books With {.Title = "ASP.NET", .ISBN = "asp1", .ReleaseDate = DateTime.Parse("11/11/2010"), .Pages = 200, .PublisherId = 1}, _
                                New Books With {.Title = "C#.NET", .ISBN = "c#2", .ReleaseDate = DateTime.Parse("10/11/2010"), .Pages = 500, .PublisherId = 1}, _
                                New Books With {.Title = "VB.NET", .ISBN = "vb3", .ReleaseDate = DateTime.Parse("5/5/2009"), .Pages = 400, .PublisherId = 1}, _
                                New Books With {.Title = "SQL Server", .ISBN = "sql4", .ReleaseDate = DateTime.Parse("6/9/2010"), .Pages = 300, .PublisherId = 2}, _
                                New Books With {.Title = "JAVA", .ISBN = "java5", .ReleaseDate = DateTime.Parse("8/5/2011"), .Pages = 400, .PublisherId = 3}}

        Return lstBooks
    End Function

    Public Function GetPublishers() As List(Of Publisher)
        Dim publishers As Publisher() = { _
        New Publisher With {.PublisherId = 1, .PublisherName = "Microsoft"}, _
        New Publisher With {.PublisherId = 2, .PublisherName = "Wrox"}, _
        New Publisher With {.PublisherId = 3, .PublisherName = "Sun Publications"} _
        }
        Return New List(Of Publisher)(publishers)
    End Function