Excellent Paper, available as a download below.
Delving into Exam 70-461, the following quote from Georg Cantor is lain out at the very beginning to show the genesis of set theory and by extension SQL. Georg Cantor was the creator of mathematical set theory and defined a set as follows:
By a set we mean any collection M into a whole of definite, distinct objects m (which are called the elements of M) of our perception or of our thought.
There are more details on Cantor in this excellent documentary by Marcus De Sautoy:
Interesting presentation from Kevin Weil discussing the different NoSQL-style datastores in use at Twitter, including Hadoop (with Pig for analysis), HBase, Cassandra, and FlockDB.