Select Data Using Complied Query

Introduction

Today, in this article let's play around with an interesting and very useful concept in Entity Framework.

Question: What is a compiled query?

In simple terms "A query that is compiled once then executed several times".

Step 1: Create a new web application

Output1.jpg

Step 2: Addi a new Entity Data Model Framework

Output2.jpg

Step 3: The complete code of WebForm1.aspx looks like this:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="CompliedQuerySelectData.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>

            <table>

                <tr>

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

                        <asp:Label ID="Label1" runat="server" Text="Select Data - Complied Query" Font-Bold="true"

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

                    </td>

                </tr>

                <tr>

                    <td>

                        <asp:Label ID="Label2" runat="server" Text="Please Enter FirstName" Font-Names="Verdana"></asp:Label>

                    </td>

                    <td>

                        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

                    </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>

                <tr>

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

                        <asp:Label ID="Label3" runat="server" Font-Names="Verdana" Font-Bold="true"></asp:Label>

                    </td>

                </tr>

            </table>

        </center>

    </div>

    </form>

</body>

</html>

Step 4: 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;

using System.Data.Objects;namespace CompliedQuerySelectData

{

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

    {

        protected void Page_Load(object sender, EventArgs e)

        {

        }

        private static readonly Func<CompanyEntities, string, IQueryable<tblEmployee>> compileQuery =CompiledQuery.Compile<CompanyEntities, string, IQueryable<tblEmployee>>((objEntities, firstName) => from c in objEntities.tblEmployeewhere c.FirstName == firstNameselect c);

        protected void Button1_Click(object sender, EventArgs e)

        {

            if (string.IsNullOrEmpty(TextBox1.Text)){Label3.Text = "Please Enter Some Values";

                Label3.ForeColor = System.Drawing.Color.Red;

            }

            else

            {

                GridView1.DataSource = getData(TextBox1.Text) ;

                GridView1.DataBind();

                TextBox1.Text = string.Empty;

            }

        }

        public object getData(string firstName)

        {

            return compileQuery(objEntities, firstName);

        }

        #region Instance MembersCompanyEntities objEntities = new CompanyEntities();

        #endregion

    }

}

Step 5: The output of the application looks like this:

Output3.png


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

Output4.png


I hope this article was useful for you.