Exercise 3.19 Briefly answer the following questions based on this schema:
Emp(eid: integer, ename: string, age: integer, salary: real)Works(eid: integer, did: integer, pct_time: integer)Dept(did: integer, budget: real, managerid: integer)
1. Suppose you have a view SeniorEmp defined as follows:
CREATE VIEW SeniorEmp (sname, sage, salary)AS SELECT E.ename, E.age, E.salaryFROM Emp EWHERE E.age > 50
Explain what the system will do to process the following query:
SELECT S.snameFROM SeniorEmp SWHERE S.salary > 100,000
2. Give an example of a view on Emp that could be automatically updated by updating Emp.
3. Give an example of a view on Emp that would be impossible to update (automatically) and explain why your example presents the update problem that it does.
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