1. Acct 316 Acct 316 Acct 316 Relational Databases 4 UAA – ACCT 316 Accounting Information Systems Dr. Fred Barbee Chapter

2. Acct 316 Acct 316 Acct 316 Creating a database can be like creating a universe, only more complicated. At least when the universe was created, there was no one around to complain. Michael J. Hernandez Database Design for Mere Mortals Addison Wesley, Boston, 1997

3. Acct 316 Acct 316 Acct 316 An Out-of-the-Text Experience!

4. Acct 316 Acct 316 Acct 316 Types of Databases 4 Chapter

5. Acct 316 Acct 316 Acct 316 Types of Databases Operational Database Used whenever there is a need to collect, maintain, and modify data. Stores dynamic data (i.e., the data changes constantly and reflects up- to-the-minute information).

6. Acct 316 Acct 316 Acct 316 Types of Databases Analytical Database Used to store and track historical and time-dependent data.. Stores static data that is never (or rarely) modified. Information is applicable to a specific point in time.

7. Acct 316 Acct 316 Acct 316 Early Database Models 4 Chapter

8. Acct 316 Acct 316 Acct 316 Hierarchical Database Model Data is structured hierarchically. Visualize as an inverted tree. A single table acts as the “root” of the tree. Other tables act as branches flowing from the root.

9. Hierarchical Database Model Agents Entertainers Clients Schedule Payments Engagements

10. Acct 316 Acct 316 Acct 316 Network Database Model Visualize as an inverted tree. Several inverted trees may share branches, All of which are part of the same database structure.

11. The Network Database Model Agents Clients Entertainers Payments Musical Styles Engagements RepresentManage SchedulePerformPlayMake

12. A Basic Set Structure Relationship Owner Table Member Table Agents Clients Set Structure Represent

13. Acct 316 Acct 316 Acct 316 Enter... The Relational Database Model Relational Databases

14. Acct 316 Acct 316 Acct 316 Relational Database Model Data is stored in relations, which are perceived by the user as tables. Each relation is composed of tuples (records) and attributes (fields).

15. Fundamental Data Storage Concepts and Definitions Accounts Receivable File 2 Entities 2 Records Attributes Customer Customer Credit number name Address limit Balance Data values 301ABC Co. Box 51,000 400 555XYZ Co. Box 96,000 2,000 Individual fields

16. Acct 316 Acct 316 Acct 316 Relational Database Model The physical order of the records of fields in a table is completely immaterial. Each record in the table is identified by a field that contains a unique value.

17. A Relational Database Model Agents Clients Entertainers Musical Styles Entertainer Styles Engagements

18. Agent IDFirst NameLast NameHire DatePhone 100MikeHernandez05/16/02333-4444 101GregPiercy10/15/02444-3333 Client IDAgent IDFirst NameLast Name….. 9001100StewartJamison….. 9002101ShannonMcClain….. Agents Clients Ent IDAgent IDFirst NameLast Name….. 3000100JohnSlade….. 3001101MarkWeiser….. Client IDEnt IDEng. DateTime….. 9001300104/01/021-3 PM….. 9002300204/12/027-9 PM….. Entertainers Engagements

19. Acct 316 Acct 316 Acct 316 Now, Back to the Text

20. Acct 316 Acct 316 Acct 316 Double-Entry Vs. Database Accounting

21. Acct 316 Acct 316 Acct 316 Double-Entry Versus Database Accounting Luca Pacioli and double-entry accounting. Captures and stores key attributes of transactions in a highly aggregated form.

22. Acct 316 Acct 316 Acct 316 Double-Entry Versus Database Accounting The beloved debit/credit convention provided an important internal control feature in manual systems. Enter computerized accounting.

23. Acct 316 Acct 316 Acct 316 Double-Entry Versus Database Accounting The ability to quickly capture lots of data quickly... Date and time of purchase Identity of item purchased Store location Checkout station number Cashier number

24. Acct 316 Acct 316 Acct 316 Double-Entry Versus Database Accounting Consider a simple transaction: On November 18, 2002 we made a sale to Jones Enterprises for $10,000 on credit. Terms 2/10, n/30

25. Acct 316 Acct 316 Acct 316 How would we handle this transaction in a double-entry system?

26. Acct 316 Acct 316 Acct 316 Files Vs. Databases 4 Chapter

28. Fundamental Data Storage Concepts and Definitions Accounts Receivable File 2 Entities 2 Records Attributes Customer Customer Credit number name Address limit Balance Data values 301ABC Co. Box 51,000 400 555XYZ Co. Box 96,000 2,000 Individual fields

29. Acct 316 Acct 316 Acct 316 Basic File Types The master file, which is conceptually similar to a ledger in a manual system. The transaction file, which is conceptually similar to a journal in a manual system.

30. Acct 316 Acct 316 Acct 316 Basic File Types For many years, companies created new files and programs each time an information need arose. This proliferation of master files created problems:

31. Acct 316 Acct 316 Acct 316 Basic File Types Often the same data was stored in two or more separate files. The specific data values stored in the different files were not always consistent.

32. File-Oriented Approach Application program #1 File # 1 Item A Item B Item C Application program #2 File # 2 Item B Item D Item E

33. Acct 316 Acct 316 Acct 316 How would we handle this transaction in a relational database system.

34. Acct 316 Acct 316 Acct 316 Databases The database approach views data as an organizational resource that should be... used by, and managed for, the entire organization

35. Acct 316 Acct 316 Acct 316 Databases A database is a set of interrelated, centrally coordinated files. Focus is on Data integration Data sharing

36. Database Approach Application program #3 Application program #2 Database management system Application program #1 Item A Item B Item C Item D Item E Database

37. Database System Application program #3 Application program #2 Database management system Application program #1 Item A Item B Item C Item D Item E Database DBMS refers to programs that control the data and interfaces between the data and the application programs. The Data Base Administrator (DBA) is responsible for the database.

38. A Database Accounting System

39. Acct 316 Acct 316 Acct 316 Advantages & Disadvantages of Relational Database Systems

41. Acct 316 Acct 316 Acct 316 Advantages Reduce data storage costs Eliminate data redundancy Eliminate data inconsistencies Avoid duplicate processing

42. Acct 316 Acct 316 Acct 316 Advantages Ease add, delete, and update data maintenance tasks Make data independent of applications Centralize data management Centralize data security

43. Acct 316 Acct 316 Acct 316 Advantages Ease report modifications and updats Provide ad hoc query capabilities Facilitate cross-functional data analysis

44. Acct 316 Acct 316 Acct 316 Advantages Permit multiple users simultaneous data access.

45. Acct 316 Acct 316 Acct 316 Disadvantages Greater hardware requirements The database software itself Employing a database administrator.

46. Acct 316 Acct 316 Acct 316 Disadvantages Centralization of data... System operation becomes critical Incorrect data entry corrupts many users’ work Territorial disputes over data ownership may arise

47. Acct 316 Acct 316 Acct 316 One Last Disadvantage

48. Acct 316 Acct 316 Acct 316 It’s Your Turn! Discussion Question 4.3 p. 99

49. The text explained how database technology may eliminate the need for double-entry accounting. This creates three possibilities: The double-entry model will be abandoned, The double-entry model will not be used directly, but an external-level schema based on the double- entry model will be defined for accountant’s use; or The double entry model will be retained in database systems. Which alternative do you think is most likely to occur? Why?

50. Acct 316 Acct 316 Acct 316 Logical View Vs. Physical View

51. Acct 316 Acct 316 Acct 316 Physical View

52. Acct 316 Acct 316 Acct 316 Physical View The physical view refers to how and where the data are physically arranged and stored on disk, tape, CD-ROM, or other media.

53. Acct 316 Acct 316 Acct 316 Logical View The logical view is how the user or programmer conceptually organizes and understands the data.

55. Logical View Vs. Physical View Credit Report Customer Number Credit Limit Balance Monthly Statement Customer Name Address Balance Customer Number Customer Name Address Credit Limit Balance How data are stored on disk. Logical ViewDataPhysical View

56. Acct 316 Acct 316 Acct 316 Schemas 4 Chapter

57. Acct 316 Acct 316 Acct 316 Schemas A schema describes the logical structure of a database. There are three levels: Conceptual-Level External-Level Internal-level

58. Conceptual-Level Schema An organization-wide view of the entire database.

59. External-Level Schema Consists of a set of individual user views of portions of the database, also referred to as a subschema.

60. Internal-Level Schema The internal-level schema provides a low-level view of the database.

61. Database Management System

63. Acct 316 Acct 316 Acct 316 DBMS Languages 4 Chapter

64. Acct 316 Acct 316 Acct 316 DBMS Languages Every DBMS must provide a means of performing the three basic functions: Creating the database Changing the database Querying the database

65. Acct 316 Acct 316 Acct 316 Data Definition Language (DDL) Build the data dictionary. Initialize or create the database. Describe the logical views for each individual user or programmer. Specify any limitations or constraints on security imposed on database record or fields.

66. Acct 316 Acct 316 Acct 316 Data Manipulation Language (DML) Used for data maintenance. updating portions of the database inserting portions of the database deleting portions of the database

67. Acct 316 Acct 316 Acct 316 Data Query Language (DQL) The data query language (DQL) is used to interrogate the database. The DQL retrieves, sorts, orders, and presents subsets of the database in response to user queries.

68. Acct 316 Acct 316 Acct 316 More on the Relational Data Model 4 Chapter

69. Table in a Relational Data Model

70. Acct 316 Acct 316 Acct 316 Basic Requirements of the Relational Data Model Primary keys must be unique. The primary key cannot be null (blank). Why? Known as the entity integrity rule.

71. Acct 316 Acct 316 Acct 316 What is the entity integrity rule? The entity integrity rule ensures that every row in every relation (table) must represent data about some specific object in the real world.

72. Acct 316 Acct 316 Acct 316 Basic Requirements of the Relational Data Model Every foreign key must either be null or have a value corresponding to the value of a primary key in another relation. Why? The referential integrity rule.

73. Acct 316 Acct 316 Acct 316 What is the referential integrity rule? The referential integrity rule ensures that links exist among the tables of a database.

74. Basic Relational Data Model Stuff Relation = Table = File Some terminology

75. Table in a Relational Data Model Tuple = Row = Record Some terminology

76. Table in a Relational Data Model Attribute = Column = Field Some terminology

77. Attribute = Column = Field Each column in a table must describe a characteristic of the object identified by the primary key.

78. Attribute = Column = Field Each attribute (column) in a table has a distinct name, called the attribute name.

79. Attribute = Column = Field Every entry in a column contains a value for that column only, and the values are of the same data type.

80. Attribute = Column = Field The order (position) of the columns in relation to each other is unimportant.

81. Tuple = Row = Record The entries in each column of any row must be single valued.

82. Tuple = Row = Record The order of the rows is unimportant.

83. Tuple = Row = Record Each row is unique; it differs from all other rows in the table.

84. Three Sets of Database Terms Formal Term Less Formal Term Data Processing Term RelationTableFile TupleRowRecord AttributeColumnField

85. Acct 316 Acct 316 Acct 316 How does a database differ from a spreadsheet?

86. Acct 316 Acct 316 Acct 316 How might an accountant’s familiarity with the tabular representation of spreadsheets facilitate or hinder learning how to use a relational DBMS?

87. Acct 316 Acct 316 Acct 316 Importance of a Well- Structured Relational Database 4 Chapter

88. Acct 316 Acct 316 Acct 316 Anomalies that may occur in non- normalized relational tables.

89. Acct 316 Acct 316 Acct 316 Normalization! Anomalies! WOW! You accountants are an odd lot! What is normalization? Is anything normal around here?

90. Acct 316 Acct 316 Acct 316 Normalization A technique used to make complex databases more efficient by removing undesirable redundancy. Break one large table into several smaller tables.

91. Normalization Normalization starts with the assumption that everything is initially stored in one large table. A set of rules is then followed to decompose that initial table into a set of normalized tables. The objective is to produce a set of tables that are in what is called third normal form (3NF)

92. Acct 316 Acct 316 Acct 316 Normalization Problems caused by redundancy: Storage inefficiencies Processing inefficiencies Errors

93. Acct 316 Acct 316 Acct 316 Update Anomaly When changes (updates) to data values are not correctly recorded.

94. Acct 316 Acct 316 Acct 316 Insert Anomaly There is no way to store information about one entity in the database without it being associated with another entity

95. Acct 316 Acct 316 Acct 316 Delete Anomaly Unintended results arising from deleting a row of data pertaining to one entity and resulting in the deletion of data regarding another entity as well.

96. Acct 316 Acct 316 Acct 316 Database Design 4 Chapter

98. Acct 316 Acct 316 Acct 316 Approaches to Database Design Normalization Starts with the assumption that all data is initially stored in a large non- normalized table. This table is then decomposed using a set of normalization rules to create a set of tables in the Third Normal Form.

99. Acct 316 Acct 316 Acct 316 Approaches to Database Design Semantic Data Modeling The database designer uses his/her knowledge about the business structure to create a set of relational tables.

100. Acct 316 Acct 316 Acct 316 Database Design Objectives Completeness Relevance Accessibility Up-to-dateness flexibility

101. Acct 316 Acct 316 Acct 316 Database Design Objectives Efficiency Cost-effectiveness Integrity Security

102. Acct 316 Acct 316 Acct 316 Database Systems and the Future of Accounting Database systems have the potential to significantly alter the nature of external reporting.

103. Acct 316 Acct 316 Acct 316 Database Systems and the Future of Accounting Perhaps the most significant effect of database systems will be in the way that accounting information is used in decision making.