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Transcript
BA471 Management Information Systems Databases Database Fundamentals Once upon a time, there were files Containing data “Flat files” not databases Enter data Order System Orders Enter data Billing System Bills Enter data Inventory System Reports Database Fundamentals Systems needed each other’s data Order data needed for bills Qty data needed for orders … etc. Enter data orders System Order Orders Enter data custs Billing System Bills Enter data qty Reports Inventory System Database Fundamentals So every night, data that needed to be shared had to be copied from one system to another. Order Info transfer Cust Info Order Info transfer Qty Info Cust Info Order Info What a waste of time and resources, not to mention ….redundant! Database Fundamentals A database is: A shared collection of data that is shared and used for multiple purposes. Symbol = Database Fundamentals A database consists of Tables Made up of Rows Columns That organize data so it’s usable by people and software Database Fundamentals Advantages of database approach Minimizes redundancy Treats data as an “asset” Standardizes data “One version of the truth” Database Fundamentals Problem? Order System CUSTOMER Cust. Sat. System Sales System People Billing System Database Fundamentals A DBMS is a group of programs that interface between an actual database and a person or a PROGRAM Database Fundamentals Examples of DBMS SQL MYSQL DB2 Oracle Database Fundamentals Applications are made up of Data in databases Processes in programs Programs change – a lot – but data is stable Creating new applications: Start with the data (Another database advantage is that you CAN start with the data when designing new applications.) Database Fundamentals Step 1: Define & Analyze the data Entity: A person, place, thing or event about which you want to capture data. Relationships: Between entities. Elements or Attributes: Characteristics of entities Allowed values Database Fundamentals Data Modeling – Designing the data A narrative & schematic model Defining entities, relationships, elements, attributes Later, becomes a physical database design Database Fundamentals Banking Account Data Model Billing cycle Customer follows owns Account has Account Type Database Fundamentals Your role in Data Modeling SME Requirements analysis Data definitions Database Fundamentals In-class exercise: Western All Around Pets, Inc. Database Fundamentals Western All-Around Pets COO Mgr Exotic Pets Mgr Domestic Pets Pres & CEO CIO Controller Business Analysts Inventory Data Supervisor Database Fundamentals Data modeling – next steps Create an ERD Relational model Forward engineer a physical database (DDL) Schema Define the data Business definitions Metadata Domain Database Fundamentals Data Quality issues Ways in which data quality can be compromised Errors at data entry Software-introduced errors Deterioration over time Sabotage Honest mistakes