LINQ in Action - THE LINQ book

C# 3.0 and VB.NET 9.0 introduced implicit typing. When you use anonymous types, it's required. The rest of the time, it's mostly a judgment call to decide whether to use implicitly-typed local variables or not.
An interesting discussion is going on about this on Jean-Paul S. Boodhoo's blog. See all the comments.

Since our LINQ in Action book was published last month, we are lucky to receive a lot of nice feedback and comments. Steve, Jim, and I worked hard to make LINQ in Action a book that readers would enjoy. It's very encouraging to see what readers think about our work!
I have collected a list of reviews and quotes.

• "By far the best book available on LINQ"
• "I have the LINQ books, and this is by far the best"
• "One of the best overall tutorial texts on software development I have ever come across in 15 years"
• "LINQ in Action ROCKS!"
• "A pure pleasure to read"
• "I'm having a hard time putting down LINQ in Action, to do my actual job!"
• "One of the best .NET books ever written"
• "Best book I've read in a while"
• "I enjoy this book for its practical advice without trying to cover up any holes in the inaugural edition of LINQ"
  

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A frequent question we get about our LINQ book is whether it's been written for C# developers only. If you think so, you're making a mistake.

We cover both C# and VB.NET in the book. This is one big difference with competing books. Even if not all code samples are in both languages all the time in the book, we make sure to demonstrate and explain the differences between both languages when it makes sense.

In addition, to determine if this book is for you before buying it, you can take a look at all the resources we made available for free. This includes 3 free chapters and the source code. You can find them all on the book homepage.
The complete source code for all the code samples in the book is available as a free download. All code files and projects are provided in C# and in VB.

By the way, Jim is a VB.NET MVP. Do you think he'd been ok if we didn't cover VB in the book?

After two years of work on our LINQ book, and 10 days after the PDF ebook, here is the paper book!

 

You can buy it directly from Manning's website to receive it immediately. It will become available on Amazon and in all the other bookstores shortly.

The book already received a lot of very positive feedback! I'll share it with you soon.

Here is the preface I wrote for LINQ in Action:

I chose software development as the way to make a living mainly because it’s a technology that is constantly evolving. There’s always something new to learn. No chance of getting bored in this line of work! In addition to learning, I also enjoy teaching software development. Writing LINQ in Action was a good opportunity to both learn and teach at the same time.

When we started writing this book, LINQ was still an early prototype. We followed its evolution as it was taking shape. There was a lot to discover and a lot to understand. This is part of a software developer’s everyday job. We have to stay up-to-date with the technologies we use and learn new ones as they come out. The software development environment is evolving at an increasingly fast pace, and I don’t see any signs that that’s going to change.

.NET is a fast-moving environment. Over the last couple of years, we’ve seen two major releases of the .NET Framework, and several companion technologies have appeared: Windows Presentation Foundation, Windows Communication Foundation, Windows Workflow Foundation, ASP.NET AJAX, Silverlight, and LINQ have joined our developer toolbox. Another trend in .NET is the multiplication of programming languages. F#, which will receive the same support as C# or VB.NET in Visual Studio, introduces functional programming in .NET. Dynamic languages, such as Python and Ruby, are going to be supported by the .NET Dynamic Language Runtime.

In coming years, we’ll have to deal with more programming languages than the ones we currently master. An advantage of C#, Visual Basic, and the other .NET languages is that they are constantly adapting. C# and VB.NET have been improved in their latest versions to offer support for language-integrated querying through LINQ.

In addition to offering novel approaches to deal with data, LINQ represents a shift toward declarative and functional programming. When people ask me for reasons to learn LINQ, I tell them that they should learn it in order to be able to use it with XML, relational data, or in-memory collections, but above all to be able to start using declarative programming, deferred execution, and lambda expressions.

Start learning LINQ now! When you do, you’ll not only learn how to use this new technology, but you’ll also discover where programming is heading. One of our main goals with LINQ in Action was to help you fully comprehend the new approaches associated with LINQ.

Fabrice Marguerie

Book sent to the printer! Yeah!

Yesterday, a developer asked in the LINQ in Action forum and in Microsoft's official LINQ forum how to write a LINQ to SQL query that would return random records from the database.

It's not something built-in. There is no Random query operator provided by Microsoft. In addition, it can't be done simply by using the System.Random class, because everything in a LINQ to SQL query must be translatable to SQL.

Jim replied with several options:

• Use a pass-through query to get the results
• Use a view to return the ID of the record from tblImages from your subselect and map to that view. Then use a LINQ query to join the tblProperties through the Randomize view and then to the tblImages
• Use a scalar TSQL Function to get a random picture and include that in your LINQ query.
• Use a stored procedure to return the results.

As Jim points out, we discuss consuming pass-through queries, functions and stored procedures in chapter 8 of LINQ in Action.

Let's detail the solution that uses a SQL user-defined function. The most common way to sort records randomly is to use the NEWID SQL Server function. This is what this solution uses.

First, create the following view:

CREATE VIEW RandomView
AS
SELECT NEWID() As ID

Then create the following function that uses the view:

CREATE FUNCTION GetNewId
(
)
RETURNS uniqueidentifier
AS
BEGIN
RETURN (SELECT ID FROM RandomView)
END

The view is required because it's not possible to directly use NEWID in a scalar function.

You can then map the GetNewId user-defined function using LINQ to SQL's Function attribute. Again, see chapter 8 for the details.

That's it! You can now write LINQ queries as usual. Here is an example to pick a random object:

var tool = db.Tools.OrderBy(t => db.GetNewId()).First()

Here is another example that uses GetNewId to sort results randomly: 

var tools =
  from tool in db.Tools
  orderby db.GetNewId()
  select tool.Name;