You will begin with learning what sequences are, the data type that represents them, and the impact of deferred query execution. It can work for or against you, so its understanding is of key importance. After you learn about the deferred operators, you will then learn about nondeferred operators. By the time you are done, you will have nearly 50 operators to choose from.

Part 3, "LINQ to XML" now moves on to XML. Here you will begin by seeing the standard methods for dealing with XML by using the W3C DOM XML API. Creating XML documents this way is a nightmare that is not only hard to read, it is even harder to support. In LINQ to XML, Microsoft not only supports queries, but it fixed a number of deficiencies in the XML API.

First the author begins by showing how to create XML hierarchies in a fraction of the code; 10 lines as opposed to 29 lines. He also shows you how to create, modify and traverse XML documents as well as performing queries on an XML object.

Next he covers how to query sequences of nodes or elements using the LINQ to XML operators, and then how to perform queries on XML trees and the standard query operators that can be mingled with LINQ to XML operators to perform powerful queries. Finally he explores some additional capabilities such as performing transformations with XSLT and without. He demonstrates how to validate an XML Document against a Schema as well as performing an XPath style query.

Part 4, "LINQ to DataSet" is next up, and here you are shown how to perform queries against any dataset that has been obtained using normal ADO.NET SQL queries. This provides a more dynamic database querying interface than LINQ to SQL since LINQ to SQL can only be performed on a Microsoft SQL server.

Next you will see how to work with typed datasets. This chapter begins by showing you how to make the most of LINQ to DataSet and then follows up with some real world examples. Since the reality is that your existing code uses datasets, by using LINQ to DataSets, you can retrofit your current code to take advantage of the new technology much quicker than rewriting to use LINQ to SQL.