Understanding Database Management Systems: Structured Data for Efficient Information Handling

1. Management Information Systems, 10/e Raymond McLeod Jr. and George P. Schell Management Information Systems, 10/e Raymond McLeod and George Schell

2. Chapter 6 Database Management Systems Management Information Systems, 10/e Raymond McLeod and George Schell

3. Learning Objectives • Understand the hierarchy of data. • Understand database structures and how they work. • Know how to relate tables together in a database. • Recognize the difference between a database and a database management system. • Understand the database concept. • Know two basic methods for determining data needs. Management Information Systems, 10/e Raymond McLeod and George Schell

4. Learning Objectives (Cont’d) • Understand entity-relationship diagrams and class diagrams. • Know the basics of reports and forms. • Understand the basic difference between structured query language and query-by-example. • Know about the important personnel who are associated with databases. • Know the advantages and costs of database management systems. Management Information Systems, 10/e Raymond McLeod and George Schell

5. The Data Hierarchy • Data field is the smallest unit of data. • Record is a collection of related data fields. • File is a collection of related records. • Database is a collection of related files. • General definition • Restrictive definition Management Information Systems, 10/e Raymond McLeod and George Schell

6. Database • Table of rows and columns can be represented in a spreadsheet. • Relational database structure is conceptually similar to a collection of related tables. • Flat file is a table that does not have repeating columns; 1st normal form. • Normalization is a formal process for eliminating redundant data fields while preserving the ability of the database to add, delete, and modify records without causing errors. Management Information Systems, 10/e Raymond McLeod and George Schell

7. Figure 6.1 Spreadsheet Example of the COURSE Table Management Information Systems, 10/e Raymond McLeod and George Schell

8. Database (Cont’d) • Key in a table is a field (or combination of fields) that contain a value that uniquely identifies each record in the table. • Candidate key is a field that uniquely identifies each table row but is not the chosen key. • Relating tables is done through sharing a common field and the value of the field determines which rows in the tables are logically joined. Management Information Systems, 10/e Raymond McLeod and George Schell

9. Database Structures • Database management system (DBMS) is a software application that stores the structure of the database, the data itself, relationships among data in the database, and forms and reports pertaining to the database. • Self-describing set of related data. Management Information Systems, 10/e Raymond McLeod and George Schell

10. Hierarchical Database Structures • Hierarchical is formed by data groups, subgroups, and further subgroups; like branches on a tree. • Worked well with TPSs • Utilized computer resources efficiently • Network allows retrieval of specific records; allows a given record to point to any other record in the database. Management Information Systems, 10/e Raymond McLeod and George Schell

11. Figure 6.2 The Hierarchical Structure Between the DEPARTMENT and COURSE Tables Management Information Systems, 10/e Raymond McLeod and George Schell

12. Database Structures (Cont’d) • Relational is when the relationship between tables are implicit. • Physical relationship is when the database structure (hierarchical, network) rely on storage addresses. • Implicit relationship is when the database structure (relational) can be implied from the data. Management Information Systems, 10/e Raymond McLeod and George Schell

13. A Relational Database Example • A database named Schedule has been created from tables used earlier in the chapter and some others • The database is implemented in Microsoft Access 2002 (also known as Access XP). • Databases break information into multiple tables because if information were stored in a single table, many data field values would be duplicated. Management Information Systems, 10/e Raymond McLeod and George Schell

14. The Schedule Database • The example is implemented on Microsoft Access DBMS but would be similar on any relational DBMS product. • The COURSE table in Access (Figure 6.4) is a list of data field values. The table itself had to be defined in Access before values were entered into the data fields. • Figure 6.5 shows the definition of the Code field. • Figure 6.6 illustrates that Abbreviation field values will be looked up from a list of values in the DEPARTMENT table. • Table 6.7 shows a single table of course and department fields before they were separated into different tables. Management Information Systems, 10/e Raymond McLeod and George Schell

15. Figure 6.4 The COURSE Table in Access Management Information Systems, 10/e Raymond McLeod and George Schell

16. Figure 6.5 Defining the CODE Field Management Information Systems, 10/e Raymond McLeod and George Schell

17. Figure 6.6 Look-up Values Management Information Systems, 10/e Raymond McLeod and George Schell

18. Table 6.7 Unseperated Table of Course and Department Data Fields Management Information Systems, 10/e Raymond McLeod and George Schell

19. Figure 6.7 Access View of Tables, Fields, and their Relationships Management Information Systems, 10/e Raymond McLeod and George Schell

20. The Database Concept • Database concept is the logical integration of records across multiple physical locations. • Data independence is the ability to make changes in the data structure without making changes to the application programs that access the data. • Data dictionary includes the definition of the data stored within the database and controlled by the database management system. Management Information Systems, 10/e Raymond McLeod and George Schell

21. Creating a Database • Determine data that needs to be collected and stored is a key step. • Process-oriented approach • Define the problem. • Identify necessary decisions. • Describe information needs. • Determine the necessary processing. • Specify data needs. Management Information Systems, 10/e Raymond McLeod and George Schell

22. Determine Data Needs • Enterprise modeling approach takes a broad view of the firm’s data resources; all areas are considered, and synergy of data resources between business areas can be leveraged. • Result: Enterprise data model Management Information Systems, 10/e Raymond McLeod and George Schell

23. Figure 6.8 Creating an Enterprise Data Model Management Information Systems, 10/e Raymond McLeod and George Schell

24. Data Modeling Techniques • Entity-relationship diagrams (ERDs) is a graphical representation of data in entities and the relationships between entities. • Entity is a conceptual collection of related data fields. • Relationship is defined between entities. • One-to-one – 1:1 • One-to-many – 1:M • Many-to-many – M:N Management Information Systems, 10/e Raymond McLeod and George Schell

25. Figure 6.11 Entity-Relationship Diagram Management Information Systems, 10/e Raymond McLeod and George Schell

26. Diagramming Techniques • Class Diagram is a graphical representation of both the data used in an application and the actions associated with the data; object-oriented design model. • Objects are the data, actions taken on the data, and relationship between objects. • Class diagrams consist of the named class, fields in the class, and actions (methods) that act upon the class. Management Information Systems, 10/e Raymond McLeod and George Schell

27. Figure 6.13 Class Diagram Management Information Systems, 10/e Raymond McLeod and George Schell

28. Using the Database • Forms show one record at a time and can be used to add, delete, or modify database records. • Navigation • Accuracy • Consistency • Filtering • Subforms Management Information Systems, 10/e Raymond McLeod and George Schell

29. Figure 6.15 Combined Data Entry Form for the COURSE and PROJECT Tables Management Information Systems, 10/e Raymond McLeod and George Schell

30. Using the Database (Cont’d) • Reports are aggregated data from the database that are formatted in a manner that aids decision making. • Queries is a request for the database to display selected records. • Query-by-example (QBE) presents a standardized form that the user completes so the system can generate a true query. Management Information Systems, 10/e Raymond McLeod and George Schell

31. Figure 6.16 Report of Departments Showing Courses Offered and Course Projects Management Information Systems, 10/e Raymond McLeod and George Schell

32. Structured Query Language • Structured query language (SQL) is the code that RDBMSs use to perform their database tasks. • Method of choice for interacting with Web-based databases. • Writing SQL statements are not difficult for most manager’s data needs. Management Information Systems, 10/e Raymond McLeod and George Schell

33. Figure 6.20 Structured Query Language Code to Find Projects for the MIS105 Course Management Information Systems, 10/e Raymond McLeod and George Schell

34. Advanced Database Processing • On-line analytical processing (OLAP) allows data analysis similar to statistical cross-tabulation. • Data mining, data marts, and data warehousing focus on methodologies that offer users quick access to aggregated data specific to their decision-making needs. • Knowledge discovery analyzes data usage and data commonality among different tables. Management Information Systems, 10/e Raymond McLeod and George Schell

35. Database Personnel • Database Administrator (DBA) is an expert in developing, providing, and securing databases; duties include: • Database planning; • Database implementation; • Database operation; • Database security. Management Information Systems, 10/e Raymond McLeod and George Schell

36. Database Personnel (Cont’d) • Database programmer writes code to strip and/or aggregate data from the database • High level of specialization and selection • End user generates reports and forms, post queries to the database, and use results from their database inquiries to make decisions that affect the firm and its environmental constituents. Management Information Systems, 10/e Raymond McLeod and George Schell

37. DBMSs in Perspective • DBMS Advantages • Reduce data redundancy. • Achieve data independence. • Retrieve data and information rapidly. • Improve security. • DBMS Disadvantages • Obtain expensive software. • Obtain a large hardware configuration. • Hire and maintain a DBA staff. Management Information Systems, 10/e Raymond McLeod and George Schell