Lecture+6+Introduction+to+Database+Management+Systems+and+REA+Modeling-Student

Lecture+6+Introduction+to+Database+Management+Systems+and+REA+Modeling-Student

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Unformatted text preview: Introduction to Database Management Systems and REA Modeling Lecture 6 "Stovepiped" Systems Enterprise "stove pipes" or "silos" Enterprises typically become divided based on functional areas Each functional area typically has its own system Even within functional areas, enterprises often develop different systems for different information needs Data File for Each Application User 1 Transactions Data Program 1 A,B,C User 2 Transactions Program 2 User 3 Transactions X,B,Y Program 3 L,B,M Disadvantages of Silo Approach Data Storage - creates excessive storage costs Redundant Data same date is stored in multiple places and in different formats Data Updating - any changes or additions must be performed multiple times Task-Data Dependency - user's inability to obtain additional information as his or her needs change User 1 Transactions Database Approach One Data Repository to Support Many Applications Database Program 1 D B M S A, B, C, X, Y, L, M User 2 Transactions Program 2 User 3 Transactions Program 3 Advantages of the Database Approach Allows the creation of an integrated enterprise information system Reduces data redundancy and storage Single update Task-data independence Elements of the Database Approach System Requests System Development Process Database Administrator Applications Transactions User Programs User Programs User Programs DBMS Data Definition Language Data Manipulation Language Query Language U S E R S Transactions Host Operating System Transactions Physical Database User Queries DBMS A DBMS is an set of integrated programs designed to simplify the tasks of creating, accessing, and managing a database. It interfaces with the operating system for storage of the data on the physical media. It provides controlled access to the database. It contains a query language that non-technical users can use to access the database directly (without the aid of a programmer). REA and Relational Databases Many companies store their data in relational databases. REA modeling provides a structure for us to learn about the design of these systems. Dr. Bill McCarthy, a professor at Michigan State University, proposed this model after studying 1,000s of business transactions. Re-engineering Accounting Systems In 1982, Bill McCarthy published a research article explaining his ideas for re-engineering accounting systems He didn't call it re-engineering, but it was. He focused on natural phenomena common to most enterprises for various types of transactions. He recommended eliminating artifacts such as debits, credits, and accounts Foundation for Information System? Chart of accounts Bill McCarthy's approach: Semantic modeling --model of real-world actions --constructs have good mapping to reality --database rationale --system adaptability --value of business process analysis Modeling Allows Us To: Prepare a template that guides us in constructing a system Document the decisions we have made about a system Reality (Match Them) Victoria Memorial Hall Lincoln Memorial Mount Rushmore Reality Queen Victoria George Theodore Washington Roosevelt Abraham Lincoln Thomas Jefferson Entity-Relationship Model name location yr finished name birth death Landmark for Famous Person Famous Person Name Thomas Jefferson Abraham Lincoln Theodore Roosevelt George Washington Queen Victoria Birth 1743 1809 1858 1732 1819 Death 1826 1865 1919 1799 1901 Landmark Name Victoria Memorial Lincoln Memorial Mount Rushmore location Calcutta Washington DC South Dakota finished 1921 1922 1941 Landmark Name Victoria Memorial Lincoln Memorial Mount Rushmore location Calcutta Washington DC South Dakota finished 1921 1922 1941 For Person Queen Victoria Abraham Lincoln Abraham Lincoln, George Washington, Thomas Jefferson, Theodore Roosevelt Famous Person Name Thomas Jefferson Abraham Lincoln Theodore Roosevelt George Washington Queen Victoria Birth 1743 1809 1858 1732 1819 Death 1826 1865 1919 1799 1901 Landmark For Mount Rushmore Lincoln Memorial, Mount Rushmore Mount Rushmore Mount Rushmore Victoria Memorial Hall Landmark For Famous Person Landmark Name Victoria Memorial Lincoln Memorial Mount Rushmore Mount Rushmore Mount Rushmore Mount Rushmore Person Name Queen Victoria Abraham Lincoln Abraham Lincoln George Washington Thomas Jefferson Theodore Roosevelt Object Patterns Role in Database Design If we have knowledge (either first-hand or second-hand) about something similar in reality (and we know it is similar) we can apply our knowledge of the familiar object or situation to an unfamiliar object or situation. This is "pattern-based thinking." REA The title REA is an acronym for Resources, Events, and Agents. Events Significant operating events about which management wants information for planning, control and evaluation purposes Types: 1) Economic exchange 2) Commitment 3) Instigation Information events and decision/management events are not included. Resources Things that have economic value Should pass two tests: 1) An object of economic value associated with an event; tangible and intangible 2) Of sufficient interest that you would want to collect information about it Agents People and organizations that participate in events and about whom information is needed for planning, control, and evaluation purposes. Types 1) Internal agents 2) External agents What happened? When did it happen? Who did it? (internal and external agents) Which resources were involved and how much? Where did it happen? Characteristics of Business Events ...
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