The language designers have added powerful new features to C# that enable you to write SQL-like queries on any arbitrary sequence. Simply put, if you can foreach it, you can query it.

You don't ever have to write a complicated LINQ/Entity Framework query, but you do need to know when to call the ToList method on your query. Here's a tip on both.

You have a method that contains a LINQ query. If you use the right interface, other developers can piggyback on your method with their LINQ queries without losing efficiency.

If you start 'thinking in LINQ' you'll get more done with less code, and what you write will be simpler than using SQL.

As I mentioned Monday and in my Visual Studio 2008 review, I've been struggling with the finer points of LINQ queries. In a talkback comment to my review, "CSharper" pointed me at one solution to ...

The IQueryable interface pertaining to the System.Linq namespace extends the IEnumerable interface and can be used to query data from data sources that implement IQueryable providers.

Because I almost never write long linq queries in Linq to Objects without just converting to the pipeline-esque (or fluent if you prefer) style via extensions methods.