Introduction

Today, in this article let's play around with one of the interesting and most useful concepts in LINQ.

Question: What is inner join using LINQ with lambda?

In simple terms "It provides the flexibility to retrieve the matching result sets from two tables using LINQ with an inner join and lambda operator." .

Step 1: Create a new "ASP.NET Web Application", as in:

new-project-window.jpg

Step 2: The design of the Employee table looks like this:

employee-table.jpg

employee-ID-table.jpg

Step 3: The design of the Department table looks like this:

department-table1.jpg

department-table1.jpg

Step 4: The complete code of WebForm1.aspx looks like this:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="LINQInnerJoinApp._Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head id="Head1" runat="server">

<title></title>

</head>

<body>

<form id="form1" runat="server">

<center>

<div>

<table>

<tr>

<td colspan="2">

<asp:Label ID="Label1" runat="server" Text="INNER JOIN using LINQ with Lambda" Font-Bold="true"

Font-Size="Large" Font-Names="Verdana" ForeColor="Maroon"></asp:Label>

</td>

</tr>

<tr>

<td colspan="2" align="center">

<asp:Button ID="Button1" runat="server" Text="Select Data" Font-Names="Verdana" Width="213px"

BackColor="Orange" Font-Bold="True" OnClick="Button1_Click" />

</td>

</tr>

<tr>

<td colspan="2" align="center">

<br />

<asp:GridView ID="GridView1" runat="server" BackColor="LightGoldenrodYellow" BorderColor="Tan"

BorderWidth="1px" CellPadding="2" EnableModelValidation="True" ForeColor="Black"

GridLines="None" AutoGenerateColumns="False">

<AlternatingRowStyle BackColor="PaleGoldenrod"></AlternatingRowStyle>

<FooterStyle BackColor="Tan"></FooterStyle>

<HeaderStyle BackColor="Tan" Font-Bold="True"></HeaderStyle>

<PagerStyle HorizontalAlign="Center" BackColor="PaleGoldenrod" ForeColor="DarkSlateBlue">

</PagerStyle>

<SelectedRowStyle BackColor="DarkSlateBlue" ForeColor="GhostWhite"></SelectedRowStyle>

<Columns>

<asp:BoundField DataField="FirstName" HeaderText="First Name" ReadOnly="true" />

<asp:BoundField DataField="LastName" HeaderText="Last Name" />

<asp:BoundField DataField="DepartmentName" HeaderText="Department Name" />

</Columns>

</asp:GridView>

</td>

</tr>

</table>

</div>

</center>

</form>

</body>

</html>

Step 5: The complete code of WebForm1.aspx.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

namespace LINQInnerJoinApp

{

public partial class _Default : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

}

protected void Button1_Click(object sender, EventArgs e)

{

var query = objEntities.Employee.Join(objEntities.Department, r => r.EmpId, p => p.EmpId, (r,p) => new{r.FirstName, r.LastName, p.DepartmentName});

GridView1.DataSource = query;

GridView1.DataBind();

}

#region

Instance MembersCompanyEntities objEntities = new CompanyEntities();

#endregion

}

}

Step 6: The output of the application looks like this:


select-data.jpg

Step 7: The results retrieved output of the application looks like this:

select-data-in-linq.jpg

I hope this article is useful for you ...I look forward for your comments and feedback....Thanks Vijay Prativadi