Archive for April 5, 2007

Question 68

In a DBMS that takes in checkpoints, a system failure occurred sometime after the checkpoint as shown in the figure below. Which of the following transactions can be recovered by roll-forward?

image0921.png

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Question 67

A duplicate database with the same contents as an original database is prepared in advance. When the original database is changed, it is reflected in the duplicate data-base after a specified period of time. What is this method called?

a) Image copy
b) Mirroring
c) Replication
d) Two-phase commitment

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Question 66

Select the correct result when the following SQL statement is executed for the “Employees” and “Departments” tables below.

Employee

Employee number Post
11001 General affairs
11002 Accounting
11003 Business
11004 Business
11005 Information system
11006 Business
11008 Plan
12001 Business
12002 Information system

Section

Departments_name Floor
Plan 1
General affairs 1
Information system 2
Business 3
Accounting 2
Legal 2
Purchasing 2

SELECT COUNT(*) FROM Employees, Departments
WHERE Employees.Affiliation =Departments. Department_name
AND Departments.Floor = 2

a)1
b)2
c)3
d)4

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Question 65

Four types of VIEW are defined for the "Orders" table and the "Products" table below. Which of the following is an updatable VIEW ?

Orders

Order number Order date Customer number Customer name Product number Quantity Amount
001 2007-03-05 K111 Company A RX01 5 1,500
001 2007-03-05 K111 Company A RY01 10 2,900
001 2007-03-05 K111 Company A F001 5 3,750
002 2007-03-10 K222 Company B TV18 10 4,500
003 2007-03-15 K333 Company C TV18 5 2,250
003 2007-03-15 K333 Company C F001 2 1,500
004 2007-03-20 K222 Company B RY01 5 1,450
004 2007-03-20 K222 Company B F001 2 1,500

Product

Product number Trade name Unit cost
F001 Refrigerator 750
RX01 Radio X 300
RY01 Radio Y 290
TV18 Television 450

a) CREATE VIEW customer_V (customer_number, customer_name)
AS SELECT DISTINCT customer_number, customer_name 
FROM order

b) CREATE VIEW order_statement_V (order_number, order_day, quantity, unit cost and amount)
AS SELECT order_number, order. Products_number, quantity, unit cost, amount 
FROM order and Products 
WHERE order. Products_number = Products.Products_number

c) CREATE VIEW order_V (order_number, order_day, customer_number, total_amount)
AS SELECT order_number, order_day, customer_number, SUM (amount) 
FROM order 
GROUP BY order_number, order_day, customer_number

d) CREATE VIEW Products_V (Products_number, Products_name)
AS SELECT Products_number, Products_name
FROM Products

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Question 64

Which of the following is an appropriate statement in regard to the trigger in a relational database?

a) It is not activated by other triggers.
b) It operates when a data change operation is performed.
c) It operates when a reference command is issued.
d) It operates when the rollback process is executed.

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Question 63

The E-R diagram below represents the relationship between the entities (Customer, Product, Order, Order Breakdown) that are used by a distributor when recording product orders. Which of the following is the appropriate combination of entities that should be placed in boxes A through D in the diagram? Here, customers are assumed to be able to place orders any number of times and to order more than one product at a time. A rectangular box represents an entity set and a “1 *” between rectangular boxes denotes a one-to-many cardinality.

[A] 1 ⇔ * [B] 1 ⇔ * [C] * ⇔ 1 [D]

  A B C D
a) Customer Order Order Breakdown Product
b) Order Order Breakdown Customer Product
c) Order Breakdown Product Order Customer
d) Product Order Order Breakdown Customer

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Question 62

Which of the following is an appropriate statement concerning a logical model of a database?

a) A hierarchical model is suitable for expressing many-to-many record relationships.
b) A network model can be represented by a table that consists of rows and columns.
c) In a relational model, child record belongs to only one parent record.
d) The Boyce-Codd normal form is used in relational models.

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