Questions from Database Systems

Q: Explain why, when a manager, say Satoshi, grants an

Explain why, when a manager, say Satoshi, grants an authorization, the grant should be done by the manager role, rather than by the user Satoshi.

Q: Suppose user A, who has all authorization privileges on a relation

Suppose user A, who has all authorization privileges on a relation r, grants select on relation r to public with grant option. Suppose user B then grants select on r to A. Does this cause a cycle in t...

Q: Suppose a user creates a new relation r1 with a foreign key

Suppose a user creates a new relation r1 with a foreign key referencing another relation r2. What authorization privilege does the user need on r2? Why should this not simply be allowed without any su...

Q: Explain the difference between integrity constraints and authorization con- strains.

Explain the difference between integrity constraints and authorization con- strains.

Q: List at least two reasons why database systems support data manipulation using

List at least two reasons why database systems support data manipulation using a declarative query language such as SQL, instead of just providing a library of C or C++ functions to carry out data man...

Q: Suppose you wish to create an audit trail of changes to the

Suppose you wish to create an audit trail of changes to the takes relation. a. Define triggers to create an audit trail, logging the information into a relation called, for example, takes trail. The lo...

Q: Rewrite the query Select * From section natural join classroom

Rewrite the query Select * From section natural join classroom Without using a natural join but instead using an inner join with a using condition.

Q: Write an SQL query using the university schema to find the ID

Write an SQL query using the university schema to find the ID of each student who has never taken a course at the university. Do this using no sub queries and no set operations (use an outer join).

Q: Express the following query in SQL using no sub queries and no

Express the following query in SQL using no sub queries and no set operations.

Q: For the database of Figure 4.12, write a query

For the database of Figure 4.12, write a query to find the ID of each employee with no manager. Note that an employee may simply have no manager listed or may have a null manager. Write your query usin...