Chapter 6. Getting started with LINQ to SQL

 

This chapter covers:

  • Using LINQ to SQL to access data from SQL Server
  • The advantages of LINQ to SQL for fetching relational data
  • Updating data with LINQ to SQL

So far in this book, we’ve focused on working with data once it is already in memory. In order to query it, we need a group of items we can iterate over using the IEnumerable<T> interface. While the ability to work with data already in memory is a much-needed feature, it fails to address a large part of the picture—moving data to and from a persistence medium, typically a relational database system like SQL Server.

By this point, we should be able to handle a fairly complex LINQ to Objects query. In this chapter, we’re going to take a look at converting a query and associated classes to use LINQ to SQL rather than custom ADO.NET. We’ll start with a query that will return a listing of books that cost less than $30 and group them by their subject. This will require us to combine information from two collections: Books and Subjects. Listing 6.1 represents a possible solution to the problem at hand.

6.1. Jump into LINQ to SQL

6.2. Reading data with LINQ to SQL

6.3. Refining our queries

6.4. Working with object trees

6.5. When is my data loaded and why does it matter?

6.6. Updating data

6.7. Summary

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