Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chapter 7 Storing Organizational Information - Databases McGraw-Hill/Irwin © 2008 The McGraw-Hill Companies, All Rights Reserved Learning Outcomes 1. Define the fundamental concepts of the relational database model 2. Evaluate the advantages of the relational database model 3. Define a database management system and its relationship to a website 4. Explain why an organization would want to integrate its databases 7-2 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) 7-3 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 7-4 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 7-5 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. 7-6 Network database model A database design for storing information by linking all records that are related with a list of pointers. 7-7 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. 7-8 Tables TABLES 7-9 In the rest of this course we only focus on Relational Databases since they are far more applicable to businesses. 7-10 Entities and Attributes • Entity (tables) – a person, place, thing, transaction, or event about which information is stored – A table in relational DB is a collection of similar objects. – Rows in each table contain entity instances. – In Figure 7.1 CUSTOMER, ORDER,… are 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 7-11 Entities Attributes Keys andand Relationships Customer instance Order Attribute Fig. 7.1 7-12 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 7-13 Keys Entities andand Relationships Attributes Keys and Relationships Primary Key Foreign Key 7-14 Another example of Relationships among tables 7-15 Keys and Relationships • Potential relational database for Coca-Cola 7-16 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) 7-17 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 7-18 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. 7-19 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. 7-20 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. 7-21 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 7-22 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. 7-23 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 7-24 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. 7-25 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. 7-26 Increased Information Security • Information is an organizational asset and must be protected • Databases offer several security features including: – Password – provides authentication of the user – Access level – determines who has access to the different types of information – Access control – determines types of user access, such as read-only access 7-27 Database Management Systems • Database management systems (DBMS) – software through which users and application programs interact with a database 7-28 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/ 7-29 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 7-30 Data-Driven Business Intelligence 7-31 7-31