Union Operation Using Lambda


This article demonstrates an interesting and very useful concept in Lambda.

Question: What is union operation using Lambda?

In simple terms "It enables the performance of a union operation using a Lambda query based on the requested entities".

Step 1: Create a new web application


Step 2: Add a new ADO.NET Entity Framework model



Step 3: The complete code of WebForm1.aspx is as in the following:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="UnionLambdaApp.WebForm1" %>
<!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">
    <style type="text/css">
            margin-top: 50px;
    <form id="form1" runat="server">
                    <td colspan="2" align="center">
                        <asp:Label ID="Label1" runat="server" Text="Select Data with Lambda - UNION Operation"
                            Font-Bold="true" Font-Size="Large" Font-Names="Verdana" ForeColor="Maroon"></asp:Label>
                    <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 colspan="2" align="center">
                        <asp:GridView ID="GridView1" runat="server" CssClass="grid" BackColor="LightGoldenrodYellow"
                            BorderColor="Tan" BorderWidth="1px" CellPadding="2" ForeColor="Black" GridLines="None"
                            <AlternatingRowStyle BackColor="PaleGoldenrod" />
                            <FooterStyle BackColor="Tan" />
                            <HeaderStyle BackColor="Tan" Font-Bold="True" />
                            <PagerStyle BackColor="PaleGoldenrod" ForeColor="DarkSlateBlue" HorizontalAlign="Center" />
                            <SelectedRowStyle BackColor="DarkSlateBlue" ForeColor="GhostWhite" />
                            <SortedAscendingCellStyle BackColor="#FAFAE7" />
                            <SortedAscendingHeaderStyle BackColor="#DAC09E" />
                            <SortedDescendingCellStyle BackColor="#E1DB9C" />
                            <SortedDescendingHeaderStyle BackColor="#C2A47B" />

Step 4: The complete code of WebForm1.aspx.cs is as in the following:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;namespace UnionLambdaApp


    public partial class WebForm1 : System.Web.UI.Page


        protected void Page_Load(object sender, EventArgs e)



        protected void Button1_Click(object sender, EventArgs e)


            var query = objEntities.Customer.Select(r => r.FirstName).Union(objEntities.Employee.Select(q => q.FirstName));

            GridView1.DataSource = query;



        #region Instance MembersCompanyEntities objEntities = new CompanyEntities();


Step 5:
The output of the application is as in the following:


Step 6: The selected data output of the application is as in the following:


I hope this article was useful for you.

Up Next
    Ebook Download
    View all
    View all
    MVC Corporation is consulting and IT services based company.