1. Chapter 12: Information Systems Information systems are software applications that facilitate the organization and analysis of data. Example: Spreadsheet software allows users to place raw data in tables and then utilize formulas and basic graphical mechanisms to generate calculations and illustrations from it. Chapter 12 Information Systems Page 127

2. Database Structures Payroll Dept. Maint-enance Dept. Rental Dept. Sales Dept. Market-ing Dept. Purch-asing Dept. Sales Dept. Rental Dept. Purch-asing Dept. Advertise- ment Files Store Upkeep Files Store Personnel Files Video Sales Files Video Rental Files Video Purchase Files Integrated Database Payroll Dept. Market-ing Dept. Maint-enance Dept. An alternative to a distributed information system based upon files is a centralized system based upon the concept of databases. File-Oriented System Database-Oriented System Chapter 12 Information Systems Page 128

3. A Modular View of a Database System The DBMS uses schema and subschema to ensure data security. A schema describes the way the entire database is organized. A subschema describes the organization of the portion of the database that is accessible to a particular type of user. Chapter 12 Information Systems Page 129

4. The Relational Database Model The simplest conceptual arrangement of a database uses a table of rows (called tuples) and columns (called attributes). The major advantage of this model is its logical conceptualization. The major disadvantage is the substantial amount of software and hardware overhead required to maintain and access the table. Chapter 12 Information Systems Page 130

5. Relational Operator SELECT The SELECT operation determines which tuples have particular attributes. Apply SELECT with Price < 10.00 Chapter 12 Information Systems Page 131

6. Relational Operator PROJECT The PROJECT operation limits the scope of the database to specific attributes. Apply PROJECT with Code & Price Chapter 12 Information Systems Page 132

7. Relational Operator JOIN The JOIN operation combines multiple tables that have common attributes. Apply JOIN with CUSTOMER.RepNo = SALESREP.RepID Chapter 12 Information Systems Page 133

8. Concurrency Control A potential problem with database systems that allow multiple access points is the loss of data integrity. At ATM #1: Deposit $400 At ATM #2: Withdraw $200 Get Balance... $500 Get Balance... $500 Add $400 to Balance... $900 Subtract $200 from Balance... $300 Store new Balance... $900 Store new Balance... $300 Either balance that’s stored would be incorrect, since the correct balance is $700! Chapter 12 Information Systems Page 134

9. Databases and Privacy The proliferation of information on database systems poses a potential threat to the privacy of people about whom the data refers. Example: Medical Databases • Advantages: • Reduction of paperwork • Fewer false insurance claims • Facilitates disease tracking • Immediate access in emergency • Cost-effective ID of treatment • Safer than paper records • Disadvantages: • Employer access might cost jobs • “High risk” insurance increases • Unsolicited advertisements • Fear inhibits candid disclosure • Inaccuracies are spread easily • Dr./patient confidentiality loss Chapter 12 Information Systems Page 135

10. Cryptography Networks are set up to send messages right past stations that aren’t authorized to read them, but what’s to prevent such unauthorized viewing? Message Message The most common solution to this problem is encryption, where the message is coded in such a way that only the receiving station can decode it. Chapter 12 Information Systems Page 136

11. Public-Key Encryption I have affixed to me the dirt and dust of countless ages! Chuck mdbriugndlwg Linusmamnsgfyddkd Lucy qhgwdnchsgsh Patty ahwbsgcydhzx xsjb2dhdkWb$xzduYdm!dj5slLssghd8nd&hsnqabi?dsjsg% 1. Create Message 2. Look Up Recipient’s Public Key 3. Encrypt Message With Recipient’s Public Key 4. Transmit Encrypted Message I have affixed to me the dirt and dust of countless ages! xsjb2dhdkWb$xzduYdm!dj5slLssghd8nd&hsnqabi?dsjsg% 5. Decrypt Message With Recipient’s Private Key Chapter 12 Information Systems Page 137

12. Key-Based Authentication I’m going to recruit that funny-looking kid who plays shortstop on Chuck’s team! Ma3ndhvyr#bcjaqwpfQkguiorkfohskxi8vce%fpgkjfhikfvdamxxyemfideychssfhsgdhahdm$dlglyn7buchso 1. Create Message 2. Encrypt Message With Sender’s Private Key 3. Transmit Encrypted Message I’m going to recruit that funny-looking kid who plays shortstop on Chuck’s team! Ma3ndhvyr#bcjaqwpfQkguiorkfohskxi8vce%fpgkjfhikfvdamxxyemfideychssfhsgdhahdm$dlglyn7buchso 4. Decrypt Message With Sender’s Public Key When a message is received, how can you be sure who it came from? Chapter 12 Information Systems Page 138