INFO20003 Database Systems
Dr Renata Borovica-Gajic
INFO20003 Database Systems
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• Assignment 2 is due this Friday at 6pm
• Quiz 7 due extended to next Monday 10am
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INFO20003 Database Systems 2
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• Walkthrough
INFO20003 Database Systems 3
Quiz 6 solutions
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INFO20003 Database Systems 4
Given: Reserves (R): NTuples(R) = 100, Nkeys(sid) =100,
Sailors (S): NTuples(S) =1000, Nkeys(rating) = 10 interval [1-10], age interval [0-100], Nkeys(sid)=1000
SELECT * FROM Sailors as S INNER JOIN Reserves as R ON S.SID = R.SID WHERE rating =8 and 20< age < 30;
Calculate result size:
NTuples(S) = 1000
NTuples(R) = 100
RF(S.SID=R.SID) = ?
RF(rating) = ?
RF(20