Exercise 15.3 For each of the following SQL queries, for each relation involved, list the attributes that must be examined to compute the answer. All queries refer to the following relations:
Emp(eid: integer, did: integer, sal: integer, hobby: char(20)) Dept(did: integer, dname: char(20), floor: integer, budget: real)
1. SELECT COUNT(*) FROM Emp E, Dept D WHERE E.did = D.did
2. SELECT MAX(E.sal) FROM Emp E, Dept D WHERE E.did = D.did
3. SELECT MAX(E.sal) FROM Emp E, Dept D WHERE E.did = D.did AND D.floor = 5
4. SELECT E.did, COUNT(*) FROM Emp E, Dept D WHERE E.did = D.did GROUP BY D.did
5. SELECT D.floor, AVG(D.budget) FROM Dept D GROUP BY D.floor HAVING COUNT(*) > 2
6. SELECT D.floor, AVG(D.budget) FROM Dept D GROUP BY D.floor ORDER BY D.floor
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