ECSE 306 Lecture 11: ECSE 223 March 29
30 Aug 2018
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One time is a set, two is a beg. Example : self. persons {p1, p2} this is a set, no repetition. Or : for each administration: fo all e1, e2 in (select e from person such that e is in type of student) . In this case, we change the set that we are referring to. Constrains: person is not his or her own children. Solution1 for each person, for all c in children it is true that c<> self. Solution3 for each person: size of (select k from children such that self=k) =0.
