If you have a one-to-many relationship, and you are performing a join on the tables but you only want one record from the “many” portion of the relationship, then this is a very helpful link:
http://stackoverflow.com/questions/2281551/tsql-left-join-and-only-last-row-from-right
The outer apply appears to be very useful for joining a single row in one table to a very specific single row in another table. Not sure about efficiency, but it gets the job done.
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