LINQ is fantastic for the ability to write queries that express intent much more clearly than the same SQL, or structured code. One problem that I have run into though is handling NULL database values that are part of a group by statement.
Grouping by ProductSKU
Grouping in LINQ allows you to return sets of data from a collection for a given key value. The group by clause is what the key ends up being in the result set. Let's take a grouping of the Products by the SKU.