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.