Database Systems: Design, Implementation and Management 13th Edition solution manual

 
17. Explain why the cost of ownership may be lower with a cloud database than with a traditional, company database.
 Cloud databases reside on the Internet instead of within the organization’s own network infrastructure.  This can reduce costs because the organization is not required to purchase and maintain the hardware and software necessary to house the database and support the necessary levels of system performance.
 
 
Problem Solutions
 

ONLINE CONTENT The file structures you see in this problem set are simulated in a Microsoft Access database named Ch01_Problems, available www.cengagebrain.com.

 
Given the file structure shown in Figure P1.1, answer Problems 1 - 4.
 
FIGURE P1.1 The File Structure for Problems 1-4

 

1. How many records does the file contain? How many fields are there per record?

 
The file contains seven records (21-5Z through 31-7P) and each of the records is composed of five fields (PROJECT_CODE through PROJECT_BID_PRICE.)
 

2. What problem would you encounter if you wanted to produce a listing by city? How would you solve this problem by altering the file structure?

 
The city names are contained within the MANAGER_ADDRESS attribute and decomposing this character (string) field at the application level is cumbersome at best. (Queries become much more difficult to write and take longer to execute when internal string searches must be conducted.) If the ability to produce city listings is important, it is best to store the city name as a separate attribute.
 

3. If you wanted to produce a listing of the file contents by last name, area code, city, state, or zip code, how would you alter the file structure?

 
The more we divide the address into its component parts, the greater its information capabilities. For example, by dividing MANAGER_ADDRESS into its component parts (MGR_STREET, MGR_CITY, MGR_STATE, and MGR_ZIP), we gain the ability to easily select records on the basis of zip codes, city names, and states. Similarly, by subdividing the MANAGER name into its components MGR_LASTNAME, MGR_FIRSTNAME, and MGR_INITIAL, we gain the ability to produce more efficient searches and listings. For example, creating a phone directory is easy when you can sort by last name, first name, and initial. Finally, separating the area code and the phone number will yield the ability to efficiently group data by area codes. Thus MGR_PHONE might be decomposed into MGR_AREA_CODE and MGR_PHONE. The more you decompose the data into their component parts, the greater the search flexibility. Data that are decomposed into their most basic components are said to be atomic.
 

4. What data redundancies do you detect? How could those redundancies lead to anomalies?

 
Note that the manager named Holly B. Parker occurs three times, indicating that she manages three projects coded 21-5Z, 25-9T, and 29-2D, respectively. (The occurrences indicate that there is a 1:M relationship between PROJECT and MANAGER: each project is managed by only one manager but, apparently, a manager may manage more than one project.) Ms. Parker's phone number and address also occur three times. If Ms. Parker moves and/or changes her phone number, these changes must be made more than once and they must all be made correctly... without missing a single occurrence. If any occurrence is missed during the change, the data are "different" for the same person. After some time, it may become difficult to determine what the correct data are. In addition, multiple occurrences invite misspellings and digit transpositions, thus producing the same anomalies. The same problems exist for the multiple occurrences of George F. Dorts.
 

5. Identify and discuss the serious data redundancy problems exhibited by the file structure shown in Figure P1.5.

 
FIGURE P1.5 The File Structure for Problems 5-8