Join and GroupJoin Sequences

There are two extension methods for joining and grouping:

• Join: This method has four parameters: the sequence we want to join with, the property or properties on the left sequence to match on, the property or properties on the right sequence to match on, and a projection.

• GroupJoin: This method has the same parameters but combines the matches into a group object with a Key property for the matching value and an IEnumerable<T> type for the multiple matches.

Joining sequences

Let’s explore these methods when working with two ...