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A set of columns for which no two rows can have the exact same values.
example:
Name Age city course
A minimal combination of columns that would make the above unique would be
(Name,course) but in the case where there may be twins taking the same course
and having the same name you would have to "add in the age and time lapse btwn
each one's delivery" Therefore the superkey would be (Name, course, Age+x-minutes)
Funny ??? (: But True.