Using LINQ with ASP.NET (Part 1): ASP Alliance

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Using LINQ with ASP.NET (Part 1)

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by Scott Guthrie
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Step 5: More Fun with .NET Standard Query Operators

In addition to returning sequences of data, we can use .NET Standard Query Operators to return single or computed results of data. The below samples show examples of how to-do this:

Listing 13

<%@ Page Language="C#" CodeFile="Step5.aspx.cs"
Inherits="Step5" %>
<html>
<body>
    <form id="form1" runat="server">
    <div>
        <h1>Aggregate Value Samples</h1>
        
        <div>
            <b>Farthest Distance City:</b>
            <asp:Label ID="MaxCityNameTxt" runat="server"
Text="Label"></asp:Label>
            <asp:Label ID="MaxCityDistanceTxt" runat="server"
Text="Label"></asp:Label>
        </div>
        
        <div>
            <b>Total Travel Distance (outside of US):</b>
            <asp:Label ID="TotalDistanceTxt" runat="server"
Text="Label"></asp:Label>
        </div>        
        
        <div>
            <b>Average Distance:</b>
            <asp:Label ID="AverageDistanceTxt" runat="server"
Text="Label"></asp:Label>
        </div>        
        
    </div>
    </form>
</body>
</html>

Step5.aspx.cs code-behind file:

Listing 14

using System;
using System.Collections.Generic;
using System.Web.UI;
using System.Query;
 
public partial class Step5 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        TravelOrganizer travel = new TravelOrganizer();
 
 
        //
        // Calculate farthest city away
 
        Location farthestCity = (from location in travel.PlacesVisited
                                 orderby location.Distance descending
                                 select location).First();
 
        MaxCityNameTxt.Text = farthestCity.City;
        MaxCityDistanceTxt.Text = "(" + farthestCity.Distance + " miles)";
 
 
        //
        // Calculate total city distances of all cities outside US
 
        int totalDistance = (from location in travel.PlacesVisited
                             where location.Country != "USA"
                             select location).Sum(loc => loc.Distance);
 
        TotalDistanceTxt.Text = totalDistance + " miles";
 
 
        //
        // Calculate average city distances of each city trip
 
        double averageDistance = travel.PlacesVisited.Average(loc => loc.Distance);
 
        AverageDistanceTxt.Text = averageDistance + " miles";
    }
}

Note that the last two examples above use the new Lambda Expression support – which enable fragments of code (like delegates) that can operate on top of data to compute a result. You can build your own .NET Query Operators that use these (for example: you could build domain specific ones to calculate shipping costs or payroll tax). Everything is strongly-typed, and will support intellisense and compilation checking support.

The output of the above sample looks like so:

Figure 5

<img border=0 width=386 height=281src="/ArticleFiles/922/image005.jpg">

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User Comments

Title: linq
Name: rohit
Date: 2012-10-11 5:04:12 AM
Comment:
thanks a lot,but need more explanation

Title: uk
Name: hjkhjk
Date: 2012-07-30 2:22:48 AM
Comment:
hjkhjkhjkhjk

Title: Linq
Name: hanston
Date: 2012-06-04 2:02:15 PM
Comment:
thanks a lot....but the images aren't shown.......

Title: Language Integrated Query
Name: Daniel Kamroon
Date: 2012-03-14 7:22:12 AM
Comment:
Thank you very much. This has become my best material on LINQ topic. You made it very simple and understandable, thanks for sharing with us. Some other good articles on LINQ I was found over internet during searching this topic which also explained very well about LINQ, URL links of those posts are....
http://msdn.microsoft.com/en-us/library/bb907622.aspx
http://mindstick.com/Articles/9ca8fabd-49ef-4e4d-855b-74fc523d9138/?LINQ%20%28Language%20Integrated%20Query%29
http://www.codeproject.com/Articles/188935/LINQ-Demo-with-ASP-NET-Web-Application

Lastly, I would like to say thanks to everyone for your precious post.

Title: Sql Linq -simple query
Name: Manish Vala
Date: 2011-02-12 4:23:52 AM
Comment:
protected void Page_Load(object sender, EventArgs e)
{
//DateTime d = DateTime.Now;

string[] Name = {" Manish"," Sunil", "Rohan", "Ashok", "Mahendra" };

GridView1.DataSource = from name in Name where name.Length > 5 orderby name select name.ToUpper();
GridView1.DataBind();}

Title: SQL LINQ-A query
Name: Subhashini Janakiraman
Date: 2010-12-16 2:48:23 AM
Comment:
In the statement below which you have used,I want to know what Northwind refers to.Is it a dataset or a class?.Please reply me so.
Northwind db=new Northwind();

Title: thanks alot
Name: avrail
Date: 2010-09-26 1:38:46 AM
Comment:
thanks a lot for this article

Title: Using LINQ with ASP.NET
Name: S.Kumar
Date: 2010-04-08 3:52:48 PM
Comment:
Really a nice article, gave me a nice overview about LINQ

Title: er
Name: sdf
Date: 2009-11-14 5:46:55 AM
Comment:
protected void Page_Load(object sender, EventArgs e)
{
string[] cities = { "London", "Amsterdam", "San Francisco", "Las Vegas",
"Boston", "Raleigh", "Chicago", "Charlestown",
"Helsinki", "Nice", "Dublin" };

GridView1.DataSource = from city in cities
where city.Length > 4
orderby city
select city.ToUpper();

GridView1.DataBind();
}

Title: nice
Name: vice
Date: 2009-11-14 5:45:23 AM
Comment:
GridView1.DataSource = from city in cities
where city.Length > 4
orderby city
select city.ToUpper();

Title: jeyakumar
Name: jayakumar
Date: 2009-11-14 5:40:46 AM
Comment:
it looking like me

Title: ok
Name: kumar
Date: 2009-11-14 5:37:29 AM
Comment:
nice but not understand

Title: Topics
Name: Dhanya
Date: 2009-10-19 6:09:06 AM
Comment:
I am not understand this topics..

Title: Trying To Get a Handle On This LINQ Stuff
Name: Vibha Kant Pandey
Date: 2009-04-21 3:05:18 AM
Comment:
This article really enabled me to understand the concept of linq. the only problem i faced with this article is that i was not redirected to the correct place to download Linq May ctp

Title: About LINQs in ASP.NET
Name: SitaRamReddy.Vempada
Date: 2009-04-01 5:47:16 AM
Comment:
This article help me a lot in LINQ concept, I thank to all who are in this unit

Thanks & Regards,
srvempada

Title: Using LINQ with ASP.NET (Part 1)
Name: joseph jelasker
Date: 2009-03-28 1:52:20 AM
Comment:
This article really enabled me to understand the concept of linq. the only problem i faced with this article is that i was not redirected to the correct place to download Linq May ctp

Thanks a lot

Title: LINQ in 2005 and 2008
Name: Manigandan
Date: 2008-12-16 6:38:07 AM
Comment:
1.We are having this LINQ concept in VS2005 itself...
What is extra facility added in VS2008.

2.If i want to install LINQ separately in VS2005, What is the software that i have to install?

Title: Good one
Name: Shailendra
Date: 2008-12-09 2:24:22 AM
Comment:
Thanks for all, its very easy to know about linq from these articles.

thanks once again

Title: Trying To Get a Handle On This LINQ Stuff
Name: D Wiley
Date: 2008-11-21 9:21:36 AM
Comment:
This is on of the best walkthroughs I have seen on the subject.

Title: Leraning LINQ
Name: Manjeev kumar singh
Date: 2008-10-03 4:00:41 AM
Comment:
This one is most useful article LINQ on web. its really good start for how is beginner in LINQ....
Really thanks

Title: Using Richer Collections
Name: Nithya K
Date: 2008-09-18 6:58:04 AM
Comment:
Now i got .Its my mistake.
It is very useful

Title: Using Richer Collections
Name: Nithya K
Date: 2008-09-18 6:00:18 AM
Comment:
i got an error while executing

Title: Using Richer Collections
Name: Nithya K
Date: 2008-09-18 5:53:19 AM
Comment:
\
\S
\
\

Title: Leraning LINQ
Name: vanitha
Date: 2008-09-16 1:31:46 AM
Comment:
Very useful in learning the basic concepts of LINQ.

Title: Using LINQ with ASP.NET
Name: Durai karthik M
Date: 2008-03-15 7:20:50 AM
Comment:
Very clear to understand the LINQ concept . Keep up the good work

Title: -
Name: martin
Date: 2008-01-21 4:41:46 AM
Comment:
The images aren't shown... you need to remake the picture HTML