3-1 Chapter 3 Data and Knowledge Management

Information Systems Today (©2006 Prentice Hall) 3-2 Learning Objectives 1.Describe why databases have become so important to organizations 2.Describe what databases and database management systems are and how they work

Information Systems Today (©2006 Prentice Hall) 3-3 Database Technology A collection of related data organized in a way that makes it valuable and useful Allows organizations to retrieve, store, and analyze information easily Is vital to an organization’s success in running operations and making decisions

Information Systems Today (©2006 Prentice Hall) 3-4 Database Terminology Entities Things we store information about. (i.e. persons, places, objects, events, etc.) Have relationships to other entities (i.e. the entity Student has a relationship to the entity Grades in a University Student database Attributes These are pieces of information about an entity (i.e. Student ID, Name, etc. for the entity Student)

Information Systems Today (©2006 Prentice Hall) 3-5 Relationship of DBMS Concepts to Others?

Information Systems Today (©2006 Prentice Hall) 3-6 Levels of a Database Management System (DBMS) Database Record File / Table Field Individual characteristics about an ENTITY. Fields are also called attributes or columns depending on the type of DBMS Term A group of fields or attributes to describe a single instance of an ENTITY. These are also called rows depending on the DBMS A collection of records or instances for a given ENTITY. These are also called tables depending on the DBMS A collection of files or entities containing information to support a given system or a particular topic area Term Definitions Lowest Highest Level

Information Systems Today (©2006 Prentice Hall) 3-7 View of a Database Table or File Attribute (One Column) Record (One Row) Attribute Type

Information Systems Today (©2006 Prentice Hall) 3-8 File Processing vs Database Approach Summary File Processing Approach (Old School) Storage Media: Sequential tapes or files Data: stored in long sequential files Organization: redundant data in multiple files Efficiency: data embedded to support processing Updates: requires multiple updates in many files Processing: slower query/faster processing Data Base Approach (New School-TODAY) Storage Media: Direct Access Storage Device (DASD) Data: stored in related tables Organization: redundant data minimized/eliminated Efficiency: data only stored only in tables Updates: requires few or one update for a data field Processing: faster query/slower processing

Information Systems Today (©2006 Prentice Hall) 3-9 Advantages of the Database Approach

Information Systems Today (©2006 Prentice Hall) 3-10 Costs or Risks of the Database Approach

Information Systems Today (©2006 Prentice Hall) 3-11 Roles in Database Development and Use Database Administrator (DBA) Designs, develops and monitors performance of databases Enforces policy and standards for data uses and security Database Administrator (DBA) Designs, develops and monitors performance of databases Enforces policy and standards for data uses and security Systems Programmer Creates business applications that connect to databases Tests the new systems and databases before use Systems Programmer Creates business applications that connect to databases Tests the new systems and databases before use Systems Analyst Defines data requirements working with a DBA Incorporates the database design into new program designs Systems Analyst Defines data requirements working with a DBA Incorporates the database design into new program designs

Information Systems Today (©2006 Prentice Hall) 3-12 Database Systems Activities – Data Entry Enter Forms Employment Applications (Form Entry Screen)(Form Entry Program)(Employment DB) Example Data is entered from paper employment applications into a form entry screen The entry forms are designed to match the paper forms for easy entry The form data is processed by the entry program and then stored in the employment database

Information Systems Today (©2006 Prentice Hall) 3-13 Database Systems Activities – Query (Query Request)(Query Program)(Employment Query) SQL (Structure Query Language) A language to select and extract data from a database The industry standard language for relational databases QBE (Query by Example) A technique that allows a user to design a query on a screen by dragging and placing the query field in their desired locations Query – A database function that extracts and displays information from a database given selection parameters. Example – Display applicants entered in the last 30 days Query parameters are selected in the query request screen The database program uses SQL to query and present the result

Information Systems Today (©2006 Prentice Hall) 3-14 Database Systems Activities – Report (Query Request)(Query Program)(Employment Report) Report Generator A specialized program that uses SQL to retrieve and manipulate data (aggregate, transform, or group) Reports are designed using standard templates or can be custom generated to meet informational needs Report – A database function that extracts and formats information from a database for printing and presentation Example – Report on applicants entered in the last 30 days Report parameters are selected in the report request screen The database program uses SQL to query and present the result

Information Systems Today (©2006 Prentice Hall) 3-15 Types of DBMSs / Data Models Hierarchal Network Object-Oriented Relational –Most major industrial strength DBMSs –Oracle, MS SQL, Sybase, MySQL, etc. –Access too – so this is the one we’ll be using

Information Systems Today (©2006 Prentice Hall) 3-16 Designing Databases – Keys Primary Key A unique attribute type used to identify a single instance of an entity. It is the unique identifier of an record/row. Composite Primary Key A unique combination of attributes types used to identify a single instance of an entity. It is simply a primary key composed of multiple fields.

Information Systems Today (©2006 Prentice Hall) 3-17 Designing Databases – Keys (Example) Primary Key - Student ID ENTITIES Composite Primary Key - Student ID - Course ID - Sec No. - Term Entities are translated into Tables (Students and Grades) Entities are joined by common attributes

Information Systems Today (©2006 Prentice Hall) 3-18 Designing Databases - Associations Associations Define the relationships one entity has to another Determine necessary key structures to access data Come in three relationship types: - One-to-One - One-to-Many - Many-to-Many Foreign Key An attribute that appears as a non-primary key in one entity (table) and as a primary key attribute in another entity (table)

Information Systems Today (©2006 Prentice Hall) 3-19 Designing Databases - Associations Entity Relationship Diagram (ERD) A visual tool used to diagram and express the relationships among entities. Very useful in developing complex databases Example Each Student has only one Major (One-to-One) Each Student takes many Courses (One-to-Many) Each Student gets a Grade in her Courses For each Student and Course there is a final Grade

Information Systems Today (©2006 Prentice Hall) 3-20 The Relational Model - Normalization Normalization A technique to make complex databases more efficient by eliminating as much redundant data as possible Example: Database with redundant data (below)

Information Systems Today (©2006 Prentice Hall) 3-21 The Relational Model - Normalization Normalized Database

Information Systems Today (©2006 Prentice Hall) 3-22 Normalization in a Nutshell Normalization is simply trying to get rid of redundant data There are various forms –1 st Normal Form, 2 nd, etc. –The most commonly used in practice is 3 rd normal form. –You do NOT need to know the details of how to perform normalization – that should be taught in a database course (OPIM 205)