Select Data Using Entity Objects

Introduction
 
This article demonstrates an interesting and very useful concept in Entity Framework.
 
Question: What are entity command objects?
 
In simple terms "It enables use of entity command objects to query based on the Entity Framework".
 
Step 1: Create a new web application

datamodel.png
 
Step 2: Adding a new Entity Data Model Framework

datamodel1.png
 
Step 3: The complete code of WebForm1.aspx is as in the following:
 
 
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="EntityClientSelectData.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">
 
    <title></title>
 </
head>
 <
body>
 
    <form id="form1" runat="server">
 
        <div>
 
            <center>
 
                <div>
 
                    <table>
 
                        <tr>
 
                            <td colspan="2" align="center">
 
                                <asp:Label ID="Label1" runat="server" Text="Select Data - Entity Client" 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">
 
                                <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" />
 
                                    <EmptyDataTemplate>No Records Found!</EmptyDataTemplate>
 
                                </asp:GridView>
 
                            </td>
 
                        </tr>
 
                    </table>
 
                </div>
 
            </center>
 
        </div>
 
    </form>
 </
body>
 </
html>
 
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;
 
using System.Data.EntityClient;
 
using System.Data;
 
namespace EntityClientSelectData
 {
    
public partial class WebForm1 : System.Web.UI.Page
     {
        
protected void Page_Load(object sender, EventArgs e) { }
        
protected void Button1_Click(object sender, EventArgs e)
         {
            
using (EntityConnection objConn = new EntityConnection("name=CompanyEntities"))
             {
                 objConn.Open();
using (EntityCommand command = new EntityCommand("SELECT VALUE e FROM
 
                    CompanyEntities.tblEmployee AS e", objConn))
 
                {
                     EntityDataReader objReader = command.ExecuteReader(
CommandBehavior.SequentialAccess);
 
                    GridView1.DataSource = objReader;
                     GridView1.DataBind();
                 }
             }
         }
     }
 }
 

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

datamodel2.png
 
Step 6: The select data output of the application is as in the following:

datamodel3.png
 
I hope this article was useful for you. I look forward for your comments and feedback. Thanks Vijay.


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