I've covered the Visual Studio 2010 Historical Debugger extensively in a few of the previous posts. In this post, I'll cover how the Historical Debugger makes debugging LINQ to SQL queries a lot more convenient.

If you are trying to debug a LINQ to SQL query, often it helps to look at the generated T-SQL code to get an understanding of what the query is trying to do. In the following example, I have a very simple query expression that returns a list of customers, ordered by their CustomerID.

Dim q =
From c In db.Customers _
Order By c.CustomerID _
Select c

Using the Historical Debugger, it's super easy to see what the underlying T-SQL query looks like. That's because the Historical Debugger records queries made to the database, as seen below.

Debug History window

To see the generated T-SQL query, you can use the Autos window, as shown below.

Autos window

Once you click the Visualizer button in the Autos window, you can see the entire T-SQL statement that is generated by the LINQ to SQL query expression.

Debugger Text Visualizer

Habib Heydarian.