Inserting and Deleting records in a database using LINQ to SQL is just as easy as selecting information. What's not so easy is actually finding out how to do it. There are lots of excellent blog posts around such as this one by Scott Guthrie http://weblogs.asp.net/scottgu/archive/2007/07/11/linq-to-sql-part-4-updating-our-database.aspx, however most of them we're all written for the Beta version of LINQ to SQL which let you do a .Add() or .Remove() on your table, which was  changed on the final release. 

So to insert do something like this: 

And to delete do something like this:

LINQ to SQL is great but like all great things at some point it does something that you don't expect and gives you a headache. An example of this happened to me this week with the differences between how connection strings are handled when you LINQ to SQL model is in a class library rather than a Website or Web Application.

What makes this issue particularly annoying is that it only appears when you try and change the database server that your code is looking at which could end up being when it's going live or moving to a staging server.

So we all know about connection strings, their quite simple and you just store them in your web.config file, which is how LINQ to SQL works when your using them in a Website. But as soon as you move them to a class library things change. First your connection string name is no longer that simple name you gave it e.g. ConnectionString, now it is prefixed with the namespace which is annoying but not the end of the world. Second discovery though is no matter what you do, it just doesn't seem to pick up the connection string from the web.config file. Reason being your original connection string has now compiled itself in the class library's dll and that is what it is using.

The Solution

Depending when you discovered this the solution is not to bad as you either have a lot of code to change or only a small amount. You can always pass a connection string to the constructor when you are creating an instance of the data context e.g.

You can also set the connection string on your LINQ to SQL model to be blank, this will remove the default constructor and force you to pass a connection string. This way you web application has the choice of what connection string to use and you can keep re-using your class library in different projects.

Irrespective of if your working on some kind of company extranet or the admin side of a public facing site, one thing that will make you're clients go ooooooo and love your work is the inclusion of a funky looking chart. It may not serve any amazing purpose, but as there looking through all the boring text area's and buttons that actually make up the functionality of the site, the inclusion of nice looking chart is going to make them go "oooo that's nice" and like you even more. For those of us working in .NET, thanks' to an update from Microsoft at the end of 2008 it's also something that've very quick an easy to do. Better yet the update was free so the only cost is the time you take to implement it. 

First off if you want to use the chart's and you haven't downloaded them then that's what you need to do. The chart's shipped after .NET 3.5 so there a separate install, .NET 4 however has them included by default. 

• Chart controls for .NET 3.5
• Add on for visual studio 2008
• Chart controls samples

Using the Chart Control

Like I said adding a chart to a page is a quick and easy thing to do. Once you have the Visual Studio add on installed you can also drag and drop everything into place. However I'm going to go into a bit more detail. 

To start your going to need a data source. In this example I'm using a SQL Data Source object for ease of use, in a production environment I heavily recommend against using them as there going to make your code a completely unmanageable mess, instead I would use something like a Entity Data Source. My chart is going to be showing a graph of mobile phone handset popularity so my SQL is simply just returning a table of phone names and how many people use them. 

Code so far: 

Next we need to add a chart, the easiest way to do this is to just drag a chart object onto the page from the toolbox, however if you do want to type it yourself it's not particularly complex. 

First you will need to register the assembly on the page.. 

And then add the chart like so...

Now we're ready to start customizing what type of chart we're going to have and what data it should show from our data source.

To actually show a chart there's two bits of information you have to describe, area's and series'. The first area's is used to define an area for a chart to appear, one interesting thing about the chart control is you aren't limited to just one area. In fact in this example I'm going to have to chart's one showing a pie chart of phone popularity that will quickly show what kind of share each phone has, and then a second bar chart making it more clear the actual numbers people have of each phone. Area's also let you set properties on what the chart is actually going to look like as well. In this instance I'm going to set for both charts to be 3D.

The second bit of information is the Series. This is where you're actually specifying what data is going to be shown in which area and what kind of chart it is (e.g. Pie, Column, Donut etc). My completed code then looks like this...

Depending on your data this should give you something like this...

This is just a simple example of what you can do, but if you download the Chart Samples Project and have a look through there is no end to the possibilities with everything from different styles of charts to adding ajax functionality even with the ability to click of different parts of the carts to trigger events.