Chapter 7

1. Chapter 7 Storing Organizational Information - Databases

2. Learning Outcomes • Define the fundamental concepts of the relational database model • Evaluate the advantages of the relational database model • Define a database management system and its relationship to a website • Explain why an organization would want to integrate its databases

3. Relational Database Fundamentals • Information is everywhere in an organization • Information is stored in databases • Database (DB)– maintains information about various types of objects (inventory), events (transactions), people (employees), and places (warehouses)

4. What is the purpose of a database? • Spreadsheet and database keep track of things • Spreadsheets • Keep lists of single concept • Databases • Keep lists that involve multiple themes

5. Relational Database Fundamentals • Database models include: • Hierarchical database model– information is organized into a tree-like structure (using parent/child relationships) • Network database model– a flexible way of representing objects and their relationships; each record may have multiple parents • Relational database model– stores information in the form of logically related two-dimensional tables

6. Hierarchical database model A method for storing data in a database that looks like a family tree with one root and a number of branches or subdivisions.

7. Network database model A database design for storing information by linking all records that are related with a list of pointers.

8. Relational database model A design used in database systems in which relationships are created between one or more tables based on the idea that each pair of tables has a field in common.

9. Tables TABLES

10. In the rest of this course we only focus on Relational Databases since they are far more applicable to businesses.

11. Entities and Attributes • Entity – a person, place, thing, transaction, or event about which information is stored • A table in relation DB is a collection of similar entities. • Rows in each table contain entity instances. • In Figure 7.1 CUSTOMER includes Dave’s Sub Shop and Pizza Palace entities • Attributes (fields, columns) – characteristics or properties of an entity class • The columns in each table contain the attributes • In Figure 7.1 attributes for CUSTOMER include Customer ID, Customer Name, Contact Name

12. Keys and Relationships Entities and Attributes Customer instance Order Attribute Fig. 7.1

13. Keys and Relationships • Primary keys and foreign keys identify the various entity classes (tables) in the database • Primary key – a field (or group of fields) that uniquely identifies a given entity in a table • Foreign key – a primary key of one table that appears an attribute in another table (foreign key) and acts to provide a logical relationship among the two tables

14. Keys and Relationships Entities and Attributes Keys and Relationships Primary Key Foreign Key

15. Another example of Relationships among tables

16. Keys and Relationships • Potential relational database for Coca-Cola

17. Why Relational models • What is wrong with putting all information in the previous slide all in ONE table? • Example of multiple theme in one table ( Employer combined with position) • Example of single theme (Employer only) • Example of single theme (Position only)

18. Relational Database Advantages • Database advantages from a business perspective include • Increased flexibility • Increased scalability and performance • Reduced information redundancy • Increased information integrity (quality) • Increased information security

19. Increased Flexibility • A well-designed database should: • Handle changes quickly and easily • Provide users with different views • The physical view: of information deals with the physical storage of information on a storage device such as a hard disk. • The logical view: of information focuses on how users logically access information to meet their particular business needs.

20. Physical vs. logical views This separation of logical and physical views is what allows each user to access database information differently. That is, while a database has only one physical view, it can easily support multiple logical views.

21. Example • Example—a mail-order business. One user might want a CRM report presented in alphabetical format, in which case last name should appear before first name. Another user, working with a catalog mailing system, would want customer names appearing as first name and then last name. Both are easily achievable, but different logical views of the same physical information.

22. Increased Scalability and Performance • A database must scale to meet increased demand, while maintaining acceptable performance levels • Scalability – refers to how well a system can adapt to increased demands • Performance – measures how quickly a system performs a certain process or transaction

23. Increased Scalability and Performance • Some organizations must be able to support hundreds or thousands of online users including employees, partners, customers, and suppliers, who all want to access and share information.

24. Reduced Information Redundancy • Databases reduce information redundancy • Redundancy – the duplication of information or storing the same information in multiple places • Inconsistency is one of the primary problems with redundant information • Updating data without updating identical ones

25. Increase Information Integrity (Quality) • Information integrity – measures the quality of information • Integrity constraint – rules that help ensure the quality of information • There are two types of integrity constraints: • (1) relational integrity constraints and • (2) business-critical integrity constraints.

26. Types of integrity constraints • Relational integrity constraints are rules that enforce basic and fundamental information-based constraints. • Example, an integrity constraint would not allow someone to create an order for a nonexistent customer • Business-critical integrity constraints enforce business rules vital to an organization's success • Example: no product returns are accepted after 15 days past delivery.

27. Increased Information Security • Information is an organizational asset and must be protected • Databases offer several security features including: • Password – provides authentication of the user • Accesslevel – determines who has access to the different types of information • Accesscontrol – determines types of user access, such as read-only access

28. Database Management Systems • Database management systems (DBMS) – software through which users and application programs interact with a database

29. DATA-DRIVEN WEB SITES • Data-driven Web sites – an interactive Web site kept constantly updated and relevant to the needs of its customers through the use of a database – example: Amazon, ebay, http://wwwb.autotrader.ca/

30. Data-Driven Business Intelligence • Companies can gain business intelligence by viewing the data accessed and analyzed from their website. The next figure displays how running queries or using analytical tools, such as a Pivot Table, on the database that is attached to the website can offer insight into the business, such as items browsed, frequent requests, items bought together, etc. 7-30

31. Data-Driven Business Intelligence 7-31

32. Integrating Information among Multiple Databases • Integration – allows separate systems to communicate directly with each other • Forward integration – takes information entered into a given system and sends it automatically to all downstream systems and processes • Backward integration – takes information entered into a given system and sends it automatically to all upstream systems and processes

33. Integrating Information among Multiple Databases • Forward & Backward Integration

34. Integrating Information among Multiple Databases • Building a central repository specifically for integrated information