Relational Databases

CHAPTER 4 RELATIONAL DATABASES SUGGESTED ANSWERS TO DISCUSSION QUESTIONS4. 1 Contrast the logical and the physical view of data and discuss why separate views are necessary in database applications. Describe which perspective is most useful for each of the following employees: a programmer, a manager, and an internal auditor. How will understanding logical data structures assist you when designing and using database systems?4. 2 Databases are possible because of their database management system (DBMS). As shown in Figure 4. 2, the DBMS is a software program that sits between the actual data stored in the system and the application programs that use the data. As shown in Figure 4. 4, this allows users to separate the way they view the data (called the logical view) from the way the data is actually stored (the physical view). The DBMS interprets the users' requests and retrieves, manipulates, or stores the data as needed. The two distinct views separate the applications from the physi cal information, providing increased flexibility in applications, improved data security, and ease of use.In a database system, the manager will rarely need to understand or be familiar with the physical view of the data. Nor, in most instances, will the internal auditor and the programmer as most everything they do involves the logical view of the data. If accountants understand logical data structures and the logical view of the data, they are better able to manage, use, and audit a database and its data. 4. 2 The relational data model represents data as being stored in tables. Spreadsheets are another tool that accountants use to employ a tabular representation of data.What are some similarities and differences in the way these tools use tables? How might an accountant’s familiarity with the tabular representation of spreadsheets facilitate or hinder learning how to use a relational DBMS? A major difference between spreadsheets and databases is that spreadsheets are design ed primarily to handle numeric data, whereas databases can handle both text and numbers. Consequently, the query and sorting capabilities of spreadsheets are much more limited than what can be accomplished with a DBMS that has a good query language.Accountants’ familiarity with spreadsheets might hinder their ability to design and use relational DBMS because many links in spreadsheets are preprogrammed and designed in, whereas a well-designed relational database is designed to facilitate ad-hoc queries. Accountants’ familiarity with spreadsheets sometimes leads them to use a spreadsheet for a task that a database could handle much better. Over the years, the Journal of Accountancy has published a number of very good articles on how to use databases and when to use databases and when to use spreadsheets. These articles can be found on the Journal’s website: http://www. ournalofaccountancy. com/4. 3 Some people believe database technology may eliminate the need fo r double-entry accounting. This creates three possibilities: (1) the double-entry model will be abandoned; (2) the double-entry model will not be used directly, but an external-level schema based on the double-entry model will be defined for accountants’ use; or (3) the double-entry model will be retained in database systems. Which alternative do you think is most likely to occur? Why? There is no correct answer to this question because it is asking the student to express his opinion on what will happen in the future.Therefore, the quality of his answer depends on the justifications provided. Good answers should address the following:Database technology does permit abandonment of double entry, but there will likely be great resistance to such a radical change. Thus, students choosing this option need to present reasons why they think such a radical change would succeed.The use of a schema for accountants seems quite plausible. It does eliminate the redundancy of double entry from the database system, yet it still provides a framework familiar and useful to accountants and financial analysts.There is a good possibility that double entry will remain, even in databases, due to inertia. Indeed, many modern AIS, such as ERP systems, use databases but also retain the principles of double entry.4. 4 Relational DBMS query languages provide easy access to information about the organization’s activities. Does this mean that online, real-time processing should be used for all transactions? Does an organization need real-time financial reports? Why or why not? ;lt;/para;gt;;lt;/question;gt;;lt;/general-problem;gt;;lt;/problemset;gt; On-line real-time processing is not necessary for every business transaction.For example, batch processing is adequate for payroll: there is little need for the data to be current except on payday. Real-time financial statements are useful for planning and provide management with better ability to react to changes in the environm ent. Nevertheless, real-time financial statements may present distorted pictures of reality if accruals have been ignored or not properly recognized.4. 5 Why is it so important to have good data? Bad data costs businesses over $600 billion a year. Some people estimate that over 25% of business data is inaccurate or incomplete. In addition, incorrect database data can lead to bad decisions, embarrassment, and angry users. The text illustrated this with the following examples: For quite some time, a company sent half its catalogs to incorrect addresses. A manager finally investigated the large volume of returns and customer complaints and corrected the customer addresses in the database.He saved the company $12 million a year. Valparaiso, Indiana used the county database to develop its tax rates. After mailing the tax notices, it was discovered that a $121,900 home was valued at $400 million. Due to the $3. 1 million property tax revenue shortfall, the city, the school district, and g overnmental agencies had to make severe budget cuts.   Managing data is not going to get any easier as the quantity of data generated and stored doubles every 18 months.4.6 What is a data dictionary, what does it contain, and how is it used? contains information about the structure of the database. Table 4-1 shows that there is a record in the dictionary describing each data element. The DBMS maintains the data dictionary, whose inputs include new or deleted data elements and changes in data element names, descriptions, or uses.Outputs include reports for programmers, designers, and users. These reports are used for system documentation, database design and implementation, and as part of the audit trail.4. 7   Compare and contrast the file-oriented approach and the database approach. Explain the main advantages of database systems. Information about the attributes of a customer, such as name and address, are stored in fields. Fields contain data about one entity (e. g. , one cus tomer). Multiple fields form a record. A set of related records, such as all customer records, forms a file (e. g. , the customer file).A set of interrelated, centrally coordinated files forms a database. illustrates the differences between file-oriented and database systems. In the database approach, data is an organizational resource that is used by and managed for the entire organization, not just the originating department. A database management system (DBMS) is the interface between the database and the various application programs.The database, the DBMS, and the application programs that access the database through the DBMS are referred to as the Database systems were developed to address the proliferation of master files. This proliferation created problems such as the same data stored in two or more master files. This made it difficult to integrate and update data and to obtain an organization-wide view of data.LimitAccount Balance| 4. 2Most DBMS packages contain data defini tion, data manipulation, and data query languages. For each of the following, indicate which language would be used and why. 1. A database administrator defines the logical structure of the database The DDL – this is the language used to define the database. b. The controller requests a cost accounting report containing a list of all employees being paid for more than 10 hours overtime in a given week. The DQL – this is an example of a query. c. A programmer develops a program to update the fixed-assets records stored in the database.The DML – this is the language used to actually process transaction data and update the database. d. The human resources manager requests a report noting all employees who are retiring within five years. The DQL – another example of a task that involves querying the database. e. The inventory serial number field is extended in the inventory records to allow for recognition of additional inventory items with serial numbers con taining more than 10 digits. The DDL and the DML – the former to alter the structure, the latter to make the change. f. A user develops a program to print out all purchases made during the past two weeks.The DQL – this listing can be produced by a query. g. An additional field is added to the fixed-asset records to record the estimated salvage value of each asset. The DDL and the DML – the former to add the field, the latter to enter data in it. 4. 3Ashton wants to store the following data about S;amp;S’s purchases of inventory: item numberdate of purchase vendor numbervendor address vendor namepurchase price quantity purchasedemployee number employee namepurchase order number descriptionquantity on hand extended amounttotal amount of purchase a. Design a set of relational tables to store this data.Do all of the data items need to be stored in a table? If not, which ones do not need to be stored and why do they not need to be stored? b. Identify the prima ry key for each table. c. Identify the foreign keys needed in the tables to implement referential integrity. Table Name| Primary Key| Foreign Keys| Other Attributes| Inventory| Item Number| | DescriptionQuantity on Hand| Purchases| Purchase order number| Vendor numberPurchasing Agent (employee number)| Date of purchaseTotal amount of purchase| Purchases-Inventory| Item numberPurchase order number| |Quantity purchasedUnit cost (actual)Extended amount| Vendor| Vendor number| | Vendor nameVendor address| Employees | Employee number | | Employee name| Extended amount and Total amount of purchase do not have to be stored in the database as they can be calculated from other values. Extended amount is Quantity purchased x Unit cost. Total amount of purchase is the sum of all the extended amounts for all items on a particular purchase order, d. Implement your tables using any relational database product to which you have access.Test your specification by entering sample data in each table. f. Create a few queries to retrieve or analyze the data you stored. There is no solution to parts d through f as students will select different software packages and come up with different queries. 4. 4Retrieve the S;amp;S In-Chapter Database (in Microsoft Access format) from the text’s Web site (or create the tables in a relational DBMS product).NOTE: In order to get a list of lenders without duplicates the property sheet of the query needs to be modified by setting the value of the Unique Values property to Yes. This can be seen in the screenshot below. The property sheet is found under the Design tab of the ribbon. Setting Unique Values to Yes is the equivalent of entering the DISTINCT keyword in SQL select statements. Query Result f. Which borrower requested the largest mortgage? Query Notice that in the Design section on the ribbon, you must set the Return value to 1 (located in the Query Setup group).This indicates to Access to only return the top result. See the image below for a screenshot of this. Query Result g. Which borrower requested the smallest mortgage? Query Query Result As with problem 4-10-f, you must set the Return value to 1 in the Design section of the ribbon (located in the Query Setup group). This indicates to Access to only return the top result. See the image below for a screenshot of this. SUGGESTED ANSWERS TO THE CASES 4. 1As in all areas of information technology, DBMSs are constantly