Introduction To Information Technology - Part 1 ITE271 9/2/98 ====== Information: Includes Decision Support Systems "useful data" Technology: Tools. for news articles in this class, we can live with articles from places such as news.com [the required magazine articles] Human Information Processing Model: =================================== |--------------------------E-X-E-C-U-T-I-V-E---C-O-N-T-R-O-L-------------------------------| Stimuli -------->>> sensory input --->>> *conversion* [SHORT TERM MEMORY] -> (sight, sound, et cetera) (working memory) --->>> [LONG TERM MEMORY] --->>> large capacity ***** (can retrieve from short term) includes encoding process |--------------------------E-X-E-C-U-T-I-V-E---C-O-N-T-R-O-L-------------------------------| (mastery control....controls and oversees everything...allows for FOCUS) List Format: [short term memory] : List format schemes ; related information of objects. Records: similar to a telephone? Factors which affect attention: =============================== 1) The item must have meaning to the individual 2) Similarity of difference of task 3) Complexity 4) Automaticity There are 4 types of knowledge: [internal representation of reconition] 1) Declarative - [facts, et cetera] 2) Proceedural - [how do you accomplish something?] 3) metaknowledge - [knowledge about knowledge] (allows you to filter out useless knowledge) 4) impressionistic [creative problem solving] Productivity: ============= Knowledge worker: Thinks as part of his/her job. Factors affecting productivity: Increasing productivity of knowledge worker [factoring affecting] Expansion and conversation of knowledge worker resources Make improvements to efficency [ITE tools] Limited Capabilities of Human Beings Motivation and attitude play a huge role in productivity process. This is called ARCS: [4 elements of motivation - keller] A - Attention R - Relevance C - Confidence S - Satisfaction So...in order to compensate for the limits of the Human Information Processing System [HIPS], we TEND TO REMEMBER 7 +/- 2 items. ITEMS IN OUR SHORT TERM MEMORY. To Improve Productivity: 1) Appeal to the creativity and expertise of the person 2) Do more extensive AND intensive knowledge work 3) provide for more alternatives. [this allows for more variables] 4) more complete and timely [provide for a more explicit schedule ; set priorities, et cetera] Managing Information Technology =============================== Management - Attemping to reach a goal by improving a situation or product. Automating - automate some activities [allow for use of templates or forms] Personalizing Information - require the use of todo lists and personal information systems. Personal Information Systems [PIM] ================================== Diagram of the Personal Information System Model: ================================================== routine tasks | frequenty performed tasks ================================================== non-routine tasks | infrequently performed tasks ================================================== Examples: ================================================== email | paying bills checking schedule | studying for tests ================================================== stocks | updating resume | changing majors ================================================== 9/16/98 ======= Organizational Systems Management - [large systems] Development of Large Information Systems: Formal Software Development Lifecycle: ===================================== (based on the standard software development lifecycle studied in the basic cis140/120 sequence learning how to develop and produce software ; this is a design modified for more "Real-World" use ; therefore, there is an added "0" step] Step [0] - FEASIBILITY STUDY - Conduct a study: [E S T I M A T E] Figure up: Cost Time Adaptability Compatability Scalibility Step [1] - REQUIREMENTS AND SPECIFICATIONS Gather Facts [from stakeholders] (people with vested interests) Requirements Document [Formal] People who sign the document are the bosses. (owner of company) Include the scope of completion Maintainance Contracts Training - be sure to list it in the documentational contract! Service Contract Step [2] - ANAYLSIS This is the beginning of the design process. Break down the problem into smaller problems which are easier to solve. Step [3] - DESIGN THE SOLUTION Locate the tools and research guides to do this with Involves cost calculations CAD tools Step [4] - IMPLEMENT Generate Code Purchase Equipment / Software Put things in motion Set a projected completion date Step [5] - TESTING Go back and look at your requirement specs Try to make your project fail on purpose [alpha, beta test] Perhaps open a test site to make sure everything works fine Do LOTS and LOTS and LOTS of testing spending LOTS and LOTS of time on it. STEP [6] - INSTALLATION In some cases, this is a formal step. You'll want to set a date with the client for installation. In other cases, it'll just...happen. Step [7] - MAINTAINANCE AND SUPPORT Fixing Errors Training Service Contract [be VERY EXPLICIT!!] Change / Enhance software [requires a NEW contract!] Other notes: Develop the SCOPE of the contract. Use LOTS of documentation to cover as many loopholes as possible. be sure you interview the right people and determine the best outcome. NEVER WIRE A BUILDING YOURSELF....unless you're certified. If you wire a building, and the building burns or something, you could be liable! [Class Notes] - Began 9/21/98 - Outline for tonight... 1. Role of IS for an organization. 2. Infrastructures 3. Role and Function of an information system management. 9/21/98 ======= What is an information system? There are three vital areas where information plays major role: 1) Products and Services (Info-Encyclopedia) - we're creating more and more of these which were not possible before. 2) Business Processes - "Re-Engineering" - brings about more efficency. "Saturn's just-in-time inventory" require no overhead require no warehouse deliver NOW. 3) Knowledge Work - including "databases" , Data Mining: Try to find information ; gather a lot of it together. Key Target is to find NEW information. Data Warhousing: Gathering all the information together and keep it. ...finishing up chapter two... Information Technology Infrastructure (Foundation / Framework) Easier to build Easier to maintain Easier to dispose of An Information Infrastructure is made up of four parts: a) Hardware b) Data c) Applications d) Support Personnel [the most important part of the whole system] People that: Develop Maintain Support Train Use the system 9/23/98 ======= Role and Function of Information Systems: Management is highly specialized Example: Accounting Systems pix Individual IS Example: management of an organization's information systems. Requires several specific processes. 5 tasks associated with the organization's information system: [GOOD WORDS TO HAVE ON YOUR RESUME] 1) Planning - involves both a technical plan and an organizational planning. 2) Developing and implementing applications 3) Developing, Implementing, and maintaining infrastructures. 4) Operating and maintaining the system 5) Providing support for users of the system. 10/07/98 ======== Central Processing Unit [CPU] contains: ALU - Arithmetic Logic Unit - does comparisons, et cetera CU - Control Unit - executes machine cycle Fetch an instruction -> Decode Instruction -> Execute Instruction -> Store Info 10/12/98 ======== 1) memory - RAM - Random Access Memory Data - used by programs Programs - executable Addressable - every unit of memory has an address. Voliatile Ram.....gone when power is off READ....get stuff from memory WRITE...put stuff in memory Changability - any unit of memory can be changed. ROM - Read-Only Memory Not Changable basically starts your operating system from disk and loads it into RAM Not Voliatile Cache - changable, volatile, faster, more expensive than RAM PROM - programmable ROM. Basically meant to be programmed once. FLASH - new form of nonvolatile memory CHANGABLE does not loose contents when power off 2) input / output devices Input Devices Keyboard / Mouse Output Devices monitor / printer Controlled by your operating system 3) analog vs digital Analog is a continuous signal...always changing. It has pits and hills. Continuously varying over time. Real World Examples - time, light, sound - real world "concept". In "real time". Digital - faster, 'system clock' , cheaper, easier to manipulate. Digitalizing, Simulators, et cetera. 4) Data Representation Binary Data. [bits and bytes]. Bits are nothing more than binary digits. you have either a 1 or a 0. more or less a two state system. (two states in a computer / on or off circuitry] You also have on / off curcuitry ; numbers and / or integers. First 'bit' indicates the sign. When you represent computers using decimals, you deal with scientific notation. 10/14/98 ======== READ CHAPTER 14 Encoding Data Data Representation 1. Integers 2. Reals (floats) 3. Text 4. Graphics 5. Sound Text - anything a keyboard can enter ; numbers, characters, special symbols ASCII - American Standard Code for Information Interchange "OLD" - BAUDOT- 5 bits ALL CAPS ASCII - American Standard Code for Information Interchange only uses seven 128 possible combinations of 0's and 1's. EPCIDIC - Uses all EIGHT bits Extended Binary Coded Decimal Interchange Code UNICODE - Uses SIXTEEN bits Superset of ASCII Everything contained in ASCII is also in UNICODE 0100 0001 = "A" "IBM more or less" different bases...et cetera... GRAPHICS ======== PIXEL - referring to a monitor - refers to PICTURE ELEMENTS. Greyscale...[shades of grey] Red, Green, and Blue - 255 colors a piece. "additive color model" Resolution - dependent on how many pixels you have and how far apart they are. Resolution is higher as pixels increase and dot pitch decreases. Dot pitch is the distance between each pixel on the screen. Number of Colors used....color depth Resolution is the number of horizontal and vertical rows that makes up the image. the product of the two makes up the number of pixels on the screen. The higher the resulution the higher the numbers, the better the image, but the larger the storage capacity. 10/19/98 ======== SOUND ===== Analog Signal....typically goes by sampleing rate. There are three factors which determine the quality of digital sound: 1) Sampling Rate [how close togeter are the points in time we're sampleing?] 2) How many bits are you working with? [matters in anything you work with] 3) Intended use (can determine what kind of compression you might actually USE) Examples: A Compact Disc - 44,000 samples per second. That means a 4 minute song winds up being close to 21.2 megabytes. Two basic types of compression - (for storage of ANYTHING!) 1. Lossy - You loose information ; might wish to reduce sounds you can't hear. 2. Lossless - You clearly don't loose anything ; when you decompress the information on the OTHER end..it's all back. Frequencies the HUMAN EAR can hear range between 20 to 20,000 cycles per sec. Phone can only work from 3,000 - 6,000 VIDEO ===== Video and Animation - 30 frames a second NTSC - National Television Systems Committee Standard set for frame.....211,200 [one frame] standard resolution.....480 x 440 [pixels] 3 bytes per might cost 663,600 bytes / frame required 10,008,000 bytes per second... basically looking at approximatey one gigabyte per minute.....BEFORE sound. JPEG file format: Joint Photographic Exports Group Claims Lostless Compression of 3:1 Compatable with a variety of platforms VIRTUAL REALITY =============== digital world... audio video sensory tactile smell emotion 10/21/98 ======== Began with a HECK of a quiz [which was more like a trick quiz!!] Still in chapter 14 - topic to be covered today talks about technologies - more of a historical look. we're looking at technologies which have been at the core of the processor. we're then going to move into the increase of processing power has bought us in terms of punctuality. then we're going to talk about digital storage and the storage hiarchy and the anatomy of a disk drive system. what happens when you format a disk, et cetera. we don't know how far we'll get so -- -- -- lets get started. historically we can look at disk technologies by talking about inventions - DIGITAL TECHNOLOGIES ==================== [We passed around a 'bit' (vacuum tube) and a 16K EPROM chip (small chip)] (first generation) Based on the vacuum tube. They're large, unreliable, hot, and expensive. each vacuum tube was ONE bit. From about 1939-1950's. {second generation) Based on the transistor. Smaller, cheaper, more reliable. Transistor had two main functions -- amplification and switching. (third generation) Based on Integrated Circuits. "Solid State" technology. [No moving wires, doesn't really move] (fourth generation) - been HERE for about 30 years Very Large Scale Integration. "Computer on a chip" Microprocessor. Eventually allowed for the Personal Computer. Summary: everything kept [keeps] getting smaller, faster, cheaper... Gordon Moore: One of the founders of intel. back in 1965 he made the predicition that every 18-24 months, the computing capacity would double. Things that are getting in our way: the size of an atom and the speed of light. Eventually, we're going to reach those 'limits'. ***RECEIVED HANDOUT*** - on Gordon Moore's idea. Top part of handout is from: http://www.physics.udel.edu/wwwusers/watson/scen103/intel.html Bottom part of Handout is from: http://www.intel.com/intel/museum/25anniv/Hof/moore.htm Digital Technologies - increase in processing power allows us to: 1) develop graphical user interfaces "GUI" 2) increase the power and complexity of software 3) increase the power of operating systems (which are resource managers). Therefore, as the gadgets and perifials get more and more, the OS must be more complex. 4) Encode, Process, and Store new data types. 5) Increased processing for output 6) New Input Forms - (voice recongition, more variation, et cetera) THINK ABOUT THIS: Does the increase in computing power allow developers to create new applications and do new things or do the new things they want to do demand the increase in power and storage? OPINION: The government has been a BIG driving force in computers. Next time: Talk about upper limits, talk about storage. 10/26/98 ======== What might the upper limits be? a) speed of light b) size of the atom - we don't know if storage of data will work at this size. c) electron flow throughput ========== ways we can improve our throughput - [rate of data transfer] rates risc (reduced instruction set computing) - has a smaller instruction set ; therefore, it's more efficent. cisc (compiler instructions set computing) - more complex set of instructions storage ======= (hiarchy) CPU - uses registers CACHE RAM (online storage) Hard Disk ========= Cd's, syjet, et cetera Floppy Disks Tape Storage (offline storage) Paper Storage (cost) cpu = high ; paper = low (speed) cpu = fast ; paper = slow (storage) cpu = low ; paper = more (in quantity) What determines where data is stored? Usage. registers - instructions and data cache - most recent of above ram - whole program and data that you're RUNNING. hard disk - a place you keep applications and data and OS offline objects - floppies, cd's, paper, et cetera find out how many tracks are on an ls-120 when was a ZIP drive released? 10/28/98 ======== Next time......magnetic disk technology, et cetera Finish up chapter 14 - how drives work Talk about CD technology then later on - talk about digital telecommunications CS 245 - spend a while quarter on communications end up semester with database management Magnetic Disk Storage - how it works each "ring" is a track each "pie" is a sector one chunch of "ring pie" is a track sector two track sectors is a "cluster" remember as tracks are read, you're reading a cylinder. /---\ / /-\.\ . - part of a track | \-/ | \---/ Total time - to read and write data to / from disk. Seek time - time required to find correct track Latency time - time it takes for the sector to rotate under the head Transfer time - time it takes to transfer data. Ttotal = Tseek + Tlatency + Ttransfer tracks on a hard disk / removable disk are consentric data on the inside track is denser ; more abundent ; than data on the outside tracks [because the read/write head wants to only read a set amount of data] Optical Storage =============== It's not magnetic ; you have pits and lands. Plastic Surface. Burned with a laser. (origional) Later, to read it, you also use a lower intensity laser. It either reflects back or it doesn't. CD uses a spiral track. pits and flats tracks are spiral on a cd 11/2/98 ======= Week from Wednesday, test, covering information from chapter 14 as far as we can get with digital communications. 11/11/98. CD TECHNOLOGIES =============== how is data read? constant linear velocity (clv) - data transfer rate is constant because rotational speed is changing. speed of cd changes on the inner tracks. basically 12x is the maximum speed of this type of drive. (older drives) constant angular velocity (cav?) - data is closer together on the inner spirals. similar to magnetic. (never drives) Digital Communications ====================== one-way communication model **INFO** -> SENDER -> **MEDIUM** -> RECEIVER two-way model SENDER <------> RECEIVER (info) half duplex - you can send in two directions, but only one direction at a time. full duplex - you can send in two directions, simultaniously. COMMUNICATION MEDIUMS: media types: a. guided signals: (you can take a signal and guide it) TWISTED PAIR: copper wire ; phone wire is a good example of that. ADVANTAGES: It's cheap ; It's already everywhere you need to go; it's more or less easy to install. DIS-ADVANTAGES: has a limited capacity. noise (nothing more than interference - usually electrical) ; COAXIAL CABLE: copper wire ; more insulated - ADVANTAGES: relatively cheap, but the capacity is higher. connectors are a little more complicated and they cost more. you can send more data with coaxial cable. Less noise (due to more insulation). pretty easy to install. DIS-ADVANTAGES: it's bulky. physically heavier and bigger. connectors are expensive. OPTICAL FIBER: glass wire ; transmits light. ADVANTAGES: much much less noise. higher capacity. signal actually travels further ; faster. DIS-ADVANTAGES: relatively expensive ; but it is getting cheaper. connections are expensive. it's harder to install because it is fragile. both visible and non-visible light. b. unguided mediums (wireless mediums) air ; microwave ; satellite ; cellular ; air - uses voice radio - uses a range of frequencies (bandwidth) microwave - must have a line of sight. (high frequencies) satellite - geosynchronous - some of them follow the earth's orbit. there is a small delay when working with a satellite (when you're far away). cellular - works with cells ; works through an area ; (5-10 miles or something) must be within range of a tower for it to work. infrared - very short distances c. line configurations point to point - means there is a direct path to EACH node. you have dedicated point to point and switched point to point. dedicated point to point is a "leased line". decicated line - a dedicated line which is always available to you. roughly costs 9,000 a month for a dedicated connection from mobile to new york. switched line - always have a direct connection from where you're at, but it does not always use the same path for data transfer. multi-drop line configuration - there's a line and you actually drop nodes off the line. therefore, the line is shared... --------------------------------------- | | | | | | | | | | | | | | o o o o o o o known as a 'bus topology'. courier sense multiple access (CSMA/CD) collision protection. detects a collission and handles it. ethernet is one of the most popular forms of communication. uses a bus topology. also uses protocols to handle collission - you can resend data later on. d. signal types analog: continuous signal digital: discrete signal there are four possible combinations of sending data based on these signal types. 1) we can have DIGITAL data via a DIGITAL signal - no conversion required. simple example - computer to printer. 2) can have DIGITAL data via an ANALOG signal - conversion needed. it works just like a modem -- modulate to demodulation. 10101010 <- /-\_/-\_/-\_/-\ -> 010101010 3) this would be an ANALOG signal to a DIGITAL signal. kodec - codes and decodes -- that's how you convert everything. 4) ANALOG data via ANALOG signals. monday........transmission modes and synchronous and asynchronous. 11/9/98 ======= Types of data transfer... [transmission modes] Asynchronous & Synchronous Asynchronous - you have data sent in irregular intervals. Uses start and stop bits. Synchronous - uses "timing". It's in fixed , regular intervals. because of this, you don't need start and stop bits. there is also more overhead associated with this. it requires more overhead...therefore it's more expensive.....and more efficent. It's also more accurate. bandwidth - range of frequencies. gives us capacity of communication channels. typically expressed in mhz ; millions of cycles per second. not really an appropriate term to register digital communications. bps - bits per second [baud] - better measure of digital transmission. PROTOCOLS - more or less "rules" of digital communication. two types of protocols: proprietary - organization or company owns this type. example - sna (ibm) open system - developed by committees - available to the public ethernet is a good example -- origionally propritary to xerox. protocols contain the following elements: * error correction * control * data formatting iso / osi -- international standards organization. they came up with the open systems interconnect. a model which says there are mainly 7 levels of setup...top layer using communication tool. might want to look this up for more information. iso / osi model tells you the layers and how they work together. more or less how win95 determines you have a zip file by association and calls up winzip ; et cetera. iso / osi is a standards committee. [INTERNET STUFF] TCP/IP - transmission control protocol / internet protocol. completely open system. next topic - lans, wans, man's... LAN - Local Area Network - small (in office, building, campus - et cetera) WAN - Wide Area Network - ATM's, the Internet, MAN - Metropolatin Area Network - network around the community... initially the mobile area free net...[mafn] acan is now the alabama community access network...(acan.net?) can you still get on mafn.org anymore? ROUTERS - it chooses a path on a network. it's a combination of software and hardware connects networks PACKETS - they're split up into very small packets ; they're disassembled and then re-assembiled on the other side... ================ ================ intitial message ... ... ... (several routes to source)... ... ... message recoded ================ ================ LAN TOPOLOGY- 3 different types: RING -- circular. It's not necessarily the least reliable...if a 'ring' breaks, on occasion, it just becomes a "bus". BUS -- striaght line with single connection STAR - all connected to a central server In the real world, you probably always have a hybrid network. PROBLEMS WITH NETWORKING ======================== PROBLEM: propagation delay -- it's signal degredation and intereference of noise. Also causes signal degredation. SOLUTION: repeaters - will repeat information and actually make it stronger. it tries to regenerate the same signal and send it back out. Actually has to rebuild some of the signal - otherwise it would just send out the same bad information it received. PROBLEM: noise -- it's caused by lightening at times. military used to use noise to jam other signals. (it was called ECM - electronic counter measures) all of these are interference CONSTRAINTS AND LIMITATIONS ============================ 1. limited bandwidth - the amount of the data sent over a medium has an upper boundry. 2. cost limitation - installation costs and maintainance can run up costs of a business / hobby. TECHNOLOGY CHANGE ================= What has caused change? Is it customer demand? Yup - it's called "customer push" Is it innovation? Yup - that too...this is called "customer push" Change AGENTS: (a) DIGITAL COMMUNICATIONS -- it's a huge change agent. Becuase of digital communications, a LOT has changed. Sharing information has become an ordinary experience now. Email has also changed the way we communicate. The Internet is also a new innovation from digital communications. Business operations (such as wide-panel printing) Change INHIBITORS: Hardware / Software 1) hmm..if you don't have the right hardware and software to be able to run the software, you don't have access to the newer digital communications. 2) user population is another inhibitor ; sometimes the user population can not handle the complex systems that are out there and we don't know what to do about them. (imagine UNIX!) 3) training is a problem - plus, training and software is more difficult to learn and need. Is there a need for that new wordperfect? Introduction To Information Technology [Class Notes] - Part two - Began 11/16/98 11/16/98 ======== DATA MANAGEMENT resoures to be used: pages 134-363. A lot of the information will not come from the book. During this part of the semester, we're going to be doing a lot of in class assignments and labs ; project will also be assigned to us Wednesday. References are: book, senn, james a. (information technology in business) ; Kronke, David (database processing), 1995 Access to Data: ============== 1. Access to data is critical. 2. Data is not always available electronically. 3. We are going to focus on the IT view of data management. (personal data, organizational data) organizational data - sort of the enterprise wide view of databases. probably will be on a network ; the actual data in the organization. in the old days, this was only files. files vs database: initially, you end up with inconsistant data. you also have problems maintaining the data. who is a database administrator: plans, designs, creates, maintains, and analysis the usage of a database. He/she also handled security of a database. Data Warhousing: Large databases, people look for patterns, trends, and rules while using the database. use it for decision support systems. Data mining: extracts new information from data. Tools for retrival: SQL - Structured Query Language QBE - Query by example (access uses this) External data - might be data from outside the organization Real Time Data - might be data from events (usually business events), and it's processed as it enters the system. Stored Data - must be retrived. Data that's been captured and must be retrived. transaction / event data: might record time, date, item sold, person who might have bought it, et cetera. relationship data: about entities and attributes of those entities. (could be products, customers, et cetera) generally we setup attributes for this-will be fields. summarize data: gives you statistics, et cetera reports / analysis: many times becomes the outputs of database runs. metadata: data about data. might contain data dictionaries. should help you understand or intreprit the data. Sharing Data - typically on the organizational level , you'll be sharing data and reusing data. there will be four approaches to this: file appending: (file importing) - mergeing files. works well when you have files of the same type. if you don't have files of the same type, generally you loose formatting of the file (because you have to import it) copy / paste: simply mark data ; select cut or copy ; place in another file. embedding: useful when source file and target file are created with different applications. should not change the origional data. linking: data is not copied, but a link is created for "dynamic data" -- when you update the origional document, the target data is also changed. linking (as opposed to copying) allows the target document to be smaller. considerations for choosing one of these approaches over another: ================================================================= do you need all? or part? of the file? are the files of the same type? do they use the same data structures? will the copied data be changed? if so, how? Knowledge works must be able to select the data initially, and then they must be able to limit the amount (because of the human information processing system) Characteristics of stored data: 1) existance of the data 2) accessibility of the data 3) excess of information (on overload) how does COMMUNICATION fit into all of this? =========================================== Single File System :seperate files, unrelated, unconnected, where data was kept. Also had problems keeping data organized -- might not even know if data exists. Database System - you have one owner. Therefore, you can control the information. you actually have tables (fields) of information and all the data is kept in one place. there's no compatability problem. communication gives the user of the data access to remote data. 1) enterprise database - it's a large database more or less. a corporate database. generally evolves into a centralized database. 2) eliminate data redundancy and build consistancy. 3) it's not actually entirely implementable. problems could be security, failure, et cetera.. 4) client / server databases: allocates data to a database server and assigns local responsibilities for maintainance. might use a more 'distributive' database structure. might be a payroll database. helps to remove the centralized 'bottleneck'. (you can distribute your database, or use a centralized database) reviewed data warehousing and data mining concepts. 11/18/98 ======== TERMINOLOGY What is a database? Here are its parts: Entity - something we wish to collect information about. Example might be a customer, inventory, student, et cetera. Each entity has attributes. Attributes - a "customer" entity might have these fields: (attributes): last name, address, city, balance, phone... Relationships - there's a type of database called a relational database. Microsoft Access is a relational database. Other types of databases: Relational - Idea developed by a man, E.F. Codd, around 1970. Came up with a mathmatical concept of relating data. Consists of rows and columns of information. Rows might be considered records (might also be called TUPLES) ; each column is considered to be a field. Other types of relational database systems...well - most of the systems out there seem to be relational. Hierochical Structure - you need to traverse a tree to get to the data. IBM's DL/1 is an example of this type of database. Network Database - one-to-many relationships. CODASYL / DBTG -- has a "cobol" flavor to it. (conferece on data language database task group) we'll primarily be focusing on the relational model. A transaction table might contain: date, time, customer id, et cetera. Normalization - different levels of normilization (better research this!) Primary Key - identifies each record uniquely. Typically use alphanumberic code for it. Needs to be seperate for each table. Normilization - reducing as much redundancy as possible so you don't have to repeat things at all. Index - a way of pointing to another place. Primary key is a perfect example of an index. Differences in Data Hierochys: File ==== (bottom) bits (0 or 1) bytes (character) fields (meaningful bytes - biggest link of complete data) [example: blue eyes] records (smallest complete piece of information about an entity) file Database ======== (bottom) bits (0 or 1) bytes (character) fields (meaningful bytes) [example: blue eyes] records (smallest complete piece of information about an entity) +++more complicated+++ files ; metadata ; application metadata database you've got more informaiton in your database file than you do in your actual "older" file. 11/30/98 ======== You never touch a data set. If something else goes wrong with the system, who do you think they're going to blame? ;) So...make an error report. :) 12/02/98 [ review] ======== Access to data? Data is critical to knowledge workers How do knowledge workers access data? Databases Nonelectronic data Data Warehouses External Data Organizational Data Types of data: Immediate - someone is ordering something ; capturing raw data. Real-Time - must be processed in order for it to be created. Stored - data that we must retrieve. Reusing or Sharing Data: File Appending / Importing - simply adding data from another file. Copying / Cutting and Pasting - standard clipboard operations. Embedding - copies origional data, but leaves origional data intact. Linking - points to a file and more or less - it BETTER be there. :) Remote Data: Enterprise Databases - Large databases for corporations or companies Client / Server - helps do away with the bottleneck of people trying to access Enterprise databases. Distributed - where the actual data is manipulated in seperate locations Terminology - ============= Database: A collection of related data. Entity: Anything we can collect data about. <-tables-> Attributes: Characteristics of an entity (major, name, et cetera) <-fields-> Identifiers: you name everything (your database name, your table names, anything you can name pretty much) Relationships: Similar characteristics.....[linking two tables together more or less] DBMS: [database management system] - Database Models: ================ Network database model hierarchical database model relational database modem Relational Database: tables records fields Database Management Tools: query - nothing more than a question QBE - query by example SQL - Structured Query Language Forms - you can input data easier with a form Reports - Make queries, then make reports from queries. ACM Code of Ethics: "No one should enter or use another's computing system, software, or data files without permission."