Suppose that user U creates a relation R(A,B,C,D) and wants to grant the following privileges to us W, X, and Y. Write SQL statements to achieve the above authorizations: (a) User W should be able to read all attributes/records in the relation, and be able to grant that privilege to other users. (b) User X should be able to update attributes A a D, but cannot grant that privilege to others. (c) User Y can read only attributes A, B, and only those tuples where C = 'cl'. %3|

Suppose that user U creates a relation R(A,B,C,D) and wants to grant the following privileges to us W, X, and Y. Write SQL statements to achieve the above authorizations: (a) User W should be able to read all attributes/records in the relation, and be able to grant that privilege to other users. (b) User X should be able to update attributes A a D, but cannot grant that privilege to others. (c) User Y can read only attributes A, B, and only those tuples where C = 'cl'. %3|

Database Systems: Design, Implementation, & Management

11th Edition

ISBN:9781285196145

Author:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos Coronel

Publisher:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos Coronel

Chapter10: Transaction Management And Concurrency Control

Section: Chapter Questions

Problem 1P

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Consider the following scenario: a user creates a new relation r1 that contains a foreign key that references another relation r2. The user requires what authorisation privileges on r2 in order to function properly. Why shouldn't this simply be permitted without the need for any such authorization?
Consider a view v whose definition references only relation r If a user is granted update authorization on v, does that user need to have update authorization on r as well? Why or why not?
Consider a view v whose definition references only relation r If a user is granted select authorization on v, does that user need to haveselect authorization on r as well? Why or why not?
Consider the scenario below: A user creates a new relation r1 with a foreign key referencing another relation r2. What authorization privileges does the user need on r2 for effective operation? Why should this not be permitted without such authorization?
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 such authorization?
Assume the relation r is the only reference in the view v definition. Is it required that a user with update rights on v also has update permissions on r? So what?
Consider a view v whose definition references only relation r.• If a user is granted select authorization on v, does that user need to haveselect authorization on r as well? Why or why not?• If a user is granted update authorization on v, does that user need to haveupdate authorization on r as well? Why or why not?
If we decompose a database relation R into relations R₁ and R₂, we want R₁ MR₂ R so that no tuples in R is lost. This is called the lossless join conditic 00 True False
Exercise 8.3 Consider a relation stored as a randomly ordered file for which the only index is an unclustered index on a field called sal. If you want to retrieve all records with sal > 20, is using the index always the best alternative? Explain.
Consider the following database instance. Table name: Students Primary key: sid Sid sname 7 Ricky 2 Ellen 6 MaryLou 4 Ellen Table name: Courses Primary key: cid cid cname 1 ICS 2 Finance Table name: Register Primary key: sid,cid Foreign key: sid references Students(sid) Foreign key: cid references Courses(cid) sid cid 7 2 2 2 7 1 4 1 5.1) For each of the following statements, show whether the statement is correctly executed or not (assume that the statements are executed in order, which means that if a statement is correctly executed, its effect is reflected in the following statement). If you say the statement is not executed, explain why. INSERT INTO Students VALUES (3, ‘Ellen’); INSERT INTO Students VALUES (6, ‘Ellen’); INSERT INTO Register VALUES (1, 2); INSERT INTO Courses VALUES (5, ‘Systems’); INSERT INTO Register VALUES (6, 5); INSERT INTO Register…
Please written by computer source The following relation is an extract from a restaurant point-of-sale (POS) system. The system assigns a globally unique id (GUID) to every transaction processed. CheckID comes from the pre-printed check number on the ticket used by the server for the order; these pre-printed tickets are guaranteed to be unique within the restaurant. RegisterID is which register was used for checkout and the date and time of the checkout – to the minute – are recorded in CheckoutDT; assume no two checkouts can occur at the same register in the same minute. PayType and PayTotal are, respectively, how the check was paid and what the total payment was; assume there is no splitting of a check among multiple payments. When answering the questions below use the format [attribute, attribute, …, attribute] to identify keys. 1. How many keys in general (including the empty or null key) are there in this relation? 2. Identity two multi-keys for this relation. 3. Identify two…
Consider the following database instance. Table name: Students Primary key: sid Sid sname 7 Ricky 2 Ellen 6 MaryLou 4 Ellen Table name: Courses Primary key: cid cid cname 1 ICS 2 Finance Table name: Register Primary key: sid,cid Foreign key: sid references Students(sid) Foreign key: cid references Courses(cid) sid cid 7 2 2 2 7 1 4 1 5.1) For each of the following statements, show whether the statement is correctly executed or not (assume that the statements are executed in order, which means that if a statement is correctly executed, its effect is reflected in the following statement). If you say the statement is not executed, explain why. INSERT INTO Students VALUES (3, ‘Ellen’); INSERT INTO Students VALUES (6, ‘Ellen’); INSERT INTO Register VALUES (1, 2); INSERT INTO Courses VALUES (5, ‘Systems’); INSERT INTO Register VALUES (6, 5); INSERT INTO Register…

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