Please answer a, b, c and d. 1) (30 pts) Consider the following database schema:

Question

Please answer a, b, c and d.

1) (30 pts) Consider the following database schema: Employee-(ename, setof (Children), Address, setof (Skills)) Children-[cl, c2,.., Address (city, state, zipcode) Skills s1, s2.) Assume that attributes of type setof(Children) and setof(Skills) have attribute names childrenSet and skillsSet. Suppose a database contains a relation emp (Employee). Now answer the following: a) Write a query to unnest the emp relation into flat-emp relation. b) Write a query to nest the relation flat-emp on the attribute for Children. c) Write a query to nest the relation flat-emp on the attribute for Skills. d) Write a query to nest the relation flat-emp on both the attributes for Children and Skills.

Explanation / Answer

a)

select ename, C as Children, Address.city, Address.state, Address.zipcode, S as Skills
from emp as E, E.childrenSet as C, E.skillsSet as S

b)

select ename, set(Children) as childrenSet, (city, state, zipcode) as Address, Skills
from flat-emp
groupby ename, Address, Skills

c)

select ename, Children, (city, state, zipcode) as Address, set(Skills) as skillsSet
from flat-emp
groupby ename, Children, Address

d)

select ename, set(Children) as childrenSet, (city, state, zipcode) as Address, set(Skills) as skillsSet
from flat-emp
groupby ename, Address

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