What its all about MIS 300 Chapter 3

What it’s all about MIS 300, Chapter 3

Core Concepts • Data – the source of information • Databases – where information is found • Database management – how information is maintained and used • Database applications – matching information with business needs. MIS 300, Chapter 3 2

Principles and Learning Objectives • The database approach to data management provides significant advantages over the traditional file-based approach. – Define general data management concepts and terms, highlighting the advantages of the database approach to data management. – Describe the relational database model and outline its basic features. MIS 300, Chapter 3 3

Principles and Learning Objectives -2 • A well-designed and well-managed database is an extremely valuable tool in supporting decision making. – Identify the common functions performed by all database management systems and identify popular end-user database management systems. MIS 300, Chapter 3 4

Principles and Learning Objectives -3 • The number and types of database applications will continue to evolve and yield real business benefits. – Identify and briefly discuss current database applications. MIS 300, Chapter 3 5

What is DATA? • Machine “experience”, what a machine makes of its environment Hmmmm. That feels just like “ 3” or maybe a “ 4” but definitely not a 5 THREE POINT FIVE MIS 300, Chapter 3 6

What is INFORMATION? • Human experience of Data: telling us something we didn’t know or weren’t able to predict. Was it Jones or Smith we promised the stock to? Gotta find out. Should be Smith, but… MIS 300, Chapter 3 Hey, Schmoey, Jones is here for his stock OK, and thanks for the INFORMATION! 7

The Organizational Data “Shadow” Actual Event Data “Impression” Real World Sources of Error: Spurious Data “World” Error: Lost Data MIS 300, Chapter 3 Error: Incorrect Data 8

Events as Data • Each event generates some data • The data are about the objects that play roles in the event • The data describe the objects and perhaps how they relate to one another • The events, too, relate to one another in various ways. MIS 300, Chapter 3 9

Data Events • Consider a sales “event” • It involves a number of objects: items sold, salesperson, act of selling, customer, money (objects are also called “entities”) • Each event generates data that describe each of the objects…. MIS 300, Chapter 3 10

Describing Objects • • Items sold: No. of items, item description or number Salesperson: Employee number, commission rate Act of selling: Time, date, counter Customer: Name and address or membership number MIS 300, Chapter 3 11

Data Representation: The Hierarchy of Data • Bit (a binary digit): a circuit that is either on or off • Byte: 8 bits • Character: each byte represents a character; the basic building block of information • Field: name, number, or characters that describe an aspect of a business object or activity MIS 300, Chapter 3 12

The Hierarchy of Data (continued) • • Record: a collection of related data fields File: a collection of related records Database: a collection of integrated and related files Hierarchy of data – Bits, characters, fields, records, files, and databases MIS 300, Chapter 3 13

The Hierarchy of Data (continued) Figure 3. 1: The Hierarchy of Data MIS 300, Chapter 3 14

Data Entities, Attributes, and Keys • Entity: a generalized class of people, places, or things (objects) for which data is collected, stored, and maintained • Attribute: a characteristic of an entity • Data item: a value of an attribute • Key: field(s) that identify a record • Primary key: field(s) that uniquely identify a record MIS 300, Chapter 3 15

Data Entities, Attributes, and Keys (continued) Each record is an object or event Figure 3. 2: Keys and Attributes MIS 300, Chapter 3 16

The Traditional Approach Versus the Database Approach • Traditional approach: separate data files are created for each application, i. e. , each business problem – Results in data redundancy (duplication) – Data redundancy conflicts with data integrity • Database approach: pool of related data is shared by multiple applications – Significant advantages over traditional approach – Besides, all elements of business are related MIS 300, Chapter 3 17

The Traditional Approach Figure 3. 3: The Traditional Approach to Data Management MIS 300, Chapter 3 18

The Database Approach Figure 3. 4: The Database Approach to Data Management MIS 300, Chapter 3 19

Advantages of the Database Approach Table 3. 1: Advantages of the Database Approach MIS 300, Chapter 3 20

Advantages of the Database Approach - 2 Table 3. 1: Advantages of the Database Approach (continued) MIS 300, Chapter 3 21

Disadvantages of the Database Approach Table 3. 2: Disadvantages of the Database Approach MIS 300, Chapter 3 22

Data Modeling and the Relational Database Model • When building a database, consider: – Content: What data should be collected, at what cost? – Access: What data should be provided to which users, and when? – Logical structure: How should data be arranged to make sense to a given user? – Physical organization: Where should data be physically located? MIS 300, Chapter 3 23

Data Modeling* • Building a database requires two types of design – Logical design • Shows an abstract model of how data should be structured and arranged to meet an organization’s information needs – Physical design • Fine-tunes the logical database design for performance and cost considerations * What is a model? What does it do? For whom is it useful? MIS 300, Chapter 3 24

Data Modeling (continued) • Data model: a diagram of data entities and their relationships • Entity-relationship (ER) diagrams: data models that use basic graphical symbols to show the organization of and relationships between data MIS 300, Chapter 3 25

ER Diagrams Tell a Story Entity Relationship It reads like a story… “Once upon a time there was a customer order database. In this database were salespeople, each of whom serviced one or more customers. Each customer could place one or more orders, each of which included one or more line items. Many of these line items could specify the same product. Each order generated one and only one invoice” Figure 3. 5: An Entity-Relationship (ER) Diagram for a Customer Order Database MIS 300, Chapter 3 26

The Relational Database Model • Relational model: all data elements are placed in two-dimensional tables (relations), which are the logical equivalent of files • In the relational model: – Each row of a table represents a data entity (descriptive of an object or event) – Columns of the table represent attributes • Domain: the allowable values for a given data attribute (eg. 1 -9 or “Any six-character word” or “true or false”) MIS 300, Chapter 3 27

The Relational Database Model (continued) Figure 3. 6: A Relational Database Model MIS 300, Chapter 3 28

Manipulating Data • • Selecting: eliminates rows according to criteria Projecting: eliminates columns in a table Joining: combines two or more tables Linking: relates or links two or more tables using common data attributes MIS 300, Chapter 3 29

Manipulating Data (continued) Figure 3. 8: Linking Data Tables to Answer an Inquiry MIS 300, Chapter 3 30

Database Management Systems (DBMS) • Interface between – Database and application programs – Database and the user • Database types – Flat file – Single user – Multiple users MIS 300, Chapter 3 31

Database Administration • Database administrator (DBA): directs or performs all activities to maintain a database environment – Designing, implementing, and maintaining the database system and the DBMS – Establishing policies and procedures – Training employees MIS 300, Chapter 3 32

Popular Database Management Systems • Popular DBMSs for end users: Microsoft Access and Corel Paradox • The complete database management software market includes databases by IBM, Oracle, and Microsoft • Examples of open-source database systems: Postgre. SQL and My. SQL • Many traditional database programs are now available on open-source operating systems MIS 300, Chapter 3 33

Selecting a Database Management System • Important characteristics of databases to consider: – – – – Size of the database Number of concurrent users Performance Ability to be integrated with other systems Features of the DBMS Vendor considerations Cost of the system MIS 300, Chapter 3 34

Using Databases with Other Software • Database management systems are often used with other software packages or the Internet • A database management system can act as a frontend application or a back-end application – Front-end application: interacts with users – Back-end application: interacts with applications MIS 300, Chapter 3 35

Data Warehouses, Data Marts, and Data Mining • Data warehouse: collects business information from many sources in the enterprise • Data mart: a subset of a data warehouse • Data mining: an information-analysis tool for discovering patterns and relationships in a data warehouse or a data mart MIS 300, Chapter 3 36

Data Warehouses, Data Marts, and Data Mining (continued) Figure 3. 17: Elements of a Data Warehouse MIS 300, Chapter 3 37

Data Warehouses, Data Marts, and Data Mining (continued) Table 3. 3: Common Data-Mining Applications MIS 300, Chapter 3 38

Business Intelligence • Business intelligence (BI): gathering the right information in a timely manner and usable form and analyzing it to have a positive impact on business • Knowledge management: capturing a company’s collective expertise and distributing it wherever it can help produce the biggest payoff MIS 300, Chapter 3 39

Distributed Databases • Distributed database – Data may be spread across several smaller databases connected via telecommunications devices – Corporations get more flexibility in how databases are organized and used • Replicated database – Holds a duplicate set of frequently used data MIS 300, Chapter 3 40

Online Analytical Processing (OLAP) • Software that allows users to explore data from a number of different perspectives Table 3. 4: Comparison of OLAP and Data Mining MIS 300, Chapter 3 41

Visual, Audio, and Other Database Systems • • Visual database systems Audio database systems Virtual database systems Spatial data technology MIS 300, Chapter 3 42

Summary • Hierarchy of data: bits, characters, fields, records, files, and databases • An entity is a generalized class of things (objects) for which data is collected, stored, and maintained • Attribute: characteristic of an entity • Data model: diagram of entities and relationships • Relational model: describes data in which all elements are placed in two-dimensional tables called relations MIS 300, Chapter 3 43

Summary (continued) • Selecting eliminates rows according to criteria • Projecting eliminates columns in a table • A database management system (DBMS) is a group of programs used as an interface between: – The database and application programs – The database and the user • Data dictionary: detailed description of all the data used in the database MIS 300, Chapter 3 44

Summary (continued) • Data warehouse: database that collects business information from all aspects of a company’s processes, products, and customers • Data mining: an information-analysis tool for discovering patterns and relationships in a data warehouse • An object-oriented database stores both data and its processing instructions MIS 300, Chapter 3 45