This article demonstrates an interesting and very useful concept in LINQ.
IntroductionThis article demonstrates an interesting and very useful concept in LINQ.Question: What is let keyword?In simple terms "It is a variable used to store some value, that can be then used across the query to operate with the stored value".Step 1: Create a new web applicationStep 2: Add a new entity data model frameworkStep 3: The complete code of WebForm1.aspx is as in the following:<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="LetKeywordusingLINQ.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"> .grid { margin-top: 50px; } </style> <title></title></head><body> <form id="form1" runat="server"> <center> <div> <table> <tr> <td colspan="2" align="center"> <asp:Label ID="Label1" runat="server" Text="Select Data with Let Keyword using LINQ" 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" /> </asp:GridView> </td> </tr> </table> </div> </center> </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;namespace LetKeywordusingLINQ{ 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 = from r in objEntities.tblEmployeelet bonusSal = r.Salary + 1000where bonusSal > 5000select new { FirstName = r.FirstName, LastName = r.LastName, Age = r.Age }; GridView1.DataSource = query; GridView1.DataBind(); } #region Instance MembersCompanyEntities objEntities = new CompanyEntities(); #endregion }}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.
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