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Review of Information Systems Introduction

Review of Information Systems Introduction. “Information systems” describe processes that transform data into information, using digital technology, to enable organizations to make better decisions requires inputs, outputs, processes, feedback

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Review of Information Systems Introduction

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  1. Review of Information Systems Introduction • “Information systems” describe processes that transform data into information, using digital technology, to enable organizations to make better decisions • requires inputs, outputs, processes, feedback • composed of hardware, software, databases, infrastructure, people and procedures • classified into transaction processing systems, e-commerce, management information systems and decision support systems • Computer hardware encompasses all digital machinery used to input, store, process and output data • CPU + memory is computer’s “heart”, linked to input devices, output devices, communications devices, secondary storage • Computer systems include: network computers, PCs, workstations, midrange computers, mainframes and supercomputers MIS 90-728 Lecture Notes

  2. Information Systems Introduction (cont’d) • Computer software encompasses all programs that direct hardware to perform specific tasks • types include: operating system, utility, application software • application software purchase options include: proprietary, off-the-shelf and customized • application software scope includes: personal, workgroup and enterprise • applications are developed using languages • software cost dominates organization IS total costs • The Internet is a worldwide linkage of computers that communicate • Every host sends, receives and transfers messages and has a unique URL • Internet services include e-mail, FTP/telnet, Usenet and telephony • The World Wide Web allows organized access to documents anywhere on the Internet MIS 90-728 Lecture Notes

  3. Why Do We Focus on Relational Databases? Databases are the lifeblood of any organization and answer the “who/what/when/where/why” of operations. Relational databases store large volumes of data with a minimum of data duplication, inconsistency, or anomalies, and encode key business practices Relational database management systems address the collection, storage and management of data in a relational databases, using: • Tables • Queries • User interfaces • Reports • Application programs Growth in Internet communications has increased the importance of relational database design and applications MIS 90-728 Lecture Notes

  4. Heinz School Network Information • Computer information: • Nearly 100 computers in the clusters, nearly all running Windows NT; one Mac. • Nearly 100 more computers given to staff, faculty, Ph.D students, etc. Staff and faculty machines generally run Windows 95; Ph.D student machines run Windows NT • Server information: • Five servers: Sparc and NT servers for websites, three-server setup for our Heinz domain controllers (one primary, two backups). A few stand-alone servers as well. • All servers will eventually run on Windows NT Server. • Novell vs. NT: • Novell considered more robust, more stable and less able to be hacked than Windows NT • Corporate purchasing decisions are dominating technical considerations MIS 90-728 Lecture Notes

  5. The Wide World of Heinz • The computing world at Heinz is divided into two: • The web server (domain www.heinz.cmu.edu) called Howland: a Sun Solaris machine running Unix • Howland is connected to the Andrew file system • the PC world (domain HEINZ), in which three NT servers connect all faculty, staff and student computers, web/database/Exchange servers • HEINZ domain is part of the CMU “meta-domain” CMU “meta-domain” “Unix” “NT” http://www.andrew.cmu.edu NT Server 1 http://www.heinz.cmu.edu AFS NT Server 2 NT Server 3 Communicate via FTP Howland (Heinz School webserver) Faculty, student, staff, servers MIS 90-728 Lecture Notes

  6. Overview of the Relational Database Model Relational databases can store any type of data: • IDs • Codes • Memos • Numerical Values • Hypertext Links • Images/Sounds • Date/Time • Spatial attributes • OLE All organizations use these types of data in their operations, but fewer use databases to define relationships between data MIS 90-728 Lecture Notes

  7. What data does Aardvark need? Relational Database Example: Service Delivery • Aardvark Towing , Inc. • Mission: Tow vehicles from pick up sites to destinations, charging by the mile towed. • Resources: 5 trucks, 20 drivers, radio dispatch, police scanners • Problems: Need to automate records, beat out the competition • Solution: Database, change from random to targeted truck locations MIS 90-728 Lecture Notes

  8. First Step in Relational Database Design: Identify Entity Sets Entity Set: Collection of similar persons, things, places, events, concepts, or linkages Potential Entity Sets: • TRUCK • DRIVER • VEHICLE • TOW • VEHICLE DRIVER MIS 90-728 Lecture Notes

  9. Second Step: Identify Primary Keys for Entity Sets Primary Key: Has a unique value for every entity Candidate Key: Alternate primary key MIS 90-728 Lecture Notes

  10. Third Step: Identify Attributes of Entity Sets Attribute: Characteristic or property of entities MIS 90-728 Lecture Notes

  11. Data Example: tblTruck MIS 90-728 Lecture Notes

  12. (performs a) (is used in a) VEHICLE EMPLOYEE TOW 1 M 1 M M M (drives a) 1 (is used for a) 1 TRUCK VEHICLE DRIVER Next Step: Design Entity-Relationship Diagram An entity-relationship (E-R) diagram is a blueprint of the relational database. It defines associations between and within entities that capture: connectivity, cardinality, functional relationship and others. MIS 90-728 Lecture Notes

  13. One truck can participate in many tows; Truck is a primary key for tblTruck and a foreign key for tblTow Relationships Between Tables - Example tblTruck tblTow MIS 90-728 Lecture Notes

  14. Last Step: Full Relational Database Model tblTruck (Truck#, Truck VIN, Truck Plate#, Truck Make And Model Code, Truck Year) tblEmployee (Employee#, Social Security Number, First Name, Last Name, Address, Phone, DOB) tblVehicle (Vehicle VIN, Driver#@, Vehicle Plate#, Vehicle State, Vehicle Make and Model Code, Vehicle Type, Vehicle Year, Insurance Co.) tblTow (Tow#, Truck#@, Employee#@, Vehicle VIN@, Date Towed, Time Towed, Pick Up Address, Pick Up Zone, Destination Address, Distance Towed (Miles), Comment) tblVehicleDriver (Driver#, First Name, Last Name, Operator#, Street Address, City, Zip Code, State, Phone, Owner? ) MIS 90-728 Lecture Notes

  15. What Else Is Needed to Create a RDBMS for Aardvark Towing, Inc.? • Build case for relational database management system • Learn business rules, data sources • Define and populate tables using a relational database software • Implement E-R diagram relationships • Build forms for data entry • Display spatial data in GIS • Implement spatial and aspatial queries • Design summary reports • Implementation and testing MIS 90-728 Lecture Notes

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