C# in Depth

LINQ beyond collectionsThis chapter covers■■■■■■LINQ to SQLBuilding providers with IQueryableLINQ to DataSetLINQ to XMLThird party-LINQFuture Microsoft LINQ technologiesIn the previous chapter, we saw how LINQ to Objects works, with the C# 3 compilertranslating query expressions into normal C# code, which for LINQ to Objects justhappens to call the extension methods present in the Enumerable class. Even withoutany other features, query expressions would have been useful for manipulatingdata in memory. It probably wouldn’t have been worth the extra complexity in thelanguage, though. In reality, LINQ to Objects is just one aspect of the big picture.In this chapter we’ll take a whirlwind tour of other LINQ providers and APIs.First we’ll look at LINQ to SQL, an Object Relational Mapping (ORM) solution fromMicrosoft that ships as part of .NET 3.5. After we’ve seen it working as if by magic,we’ll take a look at what’s happening behind the scenes, and how query expressionswritten in C# end up executing as SQL on the database.314Licensed to Rhona Hadida