

Many people who hear the term "relational" for the first time assume that it refers to relationships between the things in the database. This is not the case: Codd was a mathematician, and "relation" is a mathematical concept whose definition is: "Given sets S1, S2, . . ., Sn, R is a relation on these n sets if it is a set of ntuples, the first component of which is drawn from S1, the second component from S2, and so on." 




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