Reference no: EM13509225

Consider two ways to compute the names of employees who earn more than $100,000 and whose age is equal to their manager’s age. First, a nested query:

SELECT E1.ename FROM Emp E1

WHERE E1.sal > 100 AND E1.age = ( SELECT E2.age

FROM Emp E2, Dept D2 WHERE E1.dname = D2.dname

AND D2.mgr = E2.ename )

Second, a query that uses a view de?nition:

SELECT E1.ename

FROM Emp E1, MgrAge A

WHERE E1.dname = A.dname AND E1.sal > 100 AND E1.age = A.age

CREATE VIEW MgrAge (dname, age) AS SELECT D.dname, E.age

FROM Emp E, Dept D WHERE D.mgr = E.ename

1. Describe a situation in which the ?rst query is likely to outperform the second query.

2. Describe a situation in which the second query is likely to outperform the ?rst query.

3. Can you construct an equivalent query that is likely to beat both these queries when every employee who earns more than $100,000 is either 35 or 40 years old? Explain brie?y.