THE DATABASE ENVIRONMENTTHE DATABASE ENVIRONMENT

Definitions: Data, Information, Database, Metadata

File Processing SystemsThe Database ApproachComponents of the Database EnvironmentEvolution of Database Systems

Data versus InformationData versus Information

1200100

WestCharles Mann

79154 TM Shoes

Monthly Sales Report for West Region

Sales Rep: Charles MannEmp No. 79154Item Qty Sold PriceTM Shoes 1200 $100

Some DefinitionsSome Definitions

Data: Meaningful facts, text, graphics, images, sound, video segments.

Database: An organized collection of logically related data.

Information: Data processed to be useful in decision making.

Metadata: Data that describes data.

Metadata for Class RosterMetadata for Class Roster

Data Name Data Type Length Value DescriptionCOURSE Alphanumeric 30 Course ID and nameSECTION Integer 1 {1,2,...,9} Section numberSEMESTER Alphanumeric 10 Semester and yearNAME Alphanumeric 30 Student nameID Integer 9 Student IDMAJOR Alphanumeric 4 Student majorGPA Decimal 3 (0, 4.0) Student grade point average

Descriptions of the properties or characteristics of the data, including data types, field sizes, allowable values, and documentation

Three file processing systems at Three file processing systems at Pine Valley FurniturePine Valley Furniture

Disadvantages of File Processing Disadvantages of File Processing SystemsSystems

Program-Data Dependence– data descriptions are included with the application

programs that use the data

Data Redundancy (Duplication of data) Limited Data Sharing Lengthy Development Times Excessive Program Maintenance

SOLUTION: The DATABASE ApproachSOLUTION: The DATABASE Approach

Central repository of shared dataData is managed by a controlling agentStored in a standardized, convenient

form

Requires a Database Management System (DBMS)

Database Management Database Management SystemSystem

DBMS manages data resources like an operating system manages hardware resources

DBMSDBMS Databasecontainingcentralized

shared data

Application#1

Application#2

Application#3

The Database ApproachThe Database Approachemphasizes the integration and sharing of data thru the emphasizes the integration and sharing of data thru the

organizationorganization

An enterprise data model is a graphical model that shows the high-level entities for the organization and the relationship among those entities– An entity is an object or

concept that is important to the business

– ERD

Relational Databases– ORDER (O_ID, C_ID, O_Date)– ORDER_LINE (O_ID, P_ID,

QTY_Ordered)

A database application is used to perform a series of database activities (create, read, update, delete)

– The range of Database Applications

Advantages

Segment from enterprise data modelSegment from enterprise data model

Figure 3

Figure 3Segment from enterprise data model

One customer may place many orders, but each order is placed by a single customer

One-to-many relationship

Figure 3Segment from enterprise data model

One order has many order lines; each order line is associated with a single order

One-to-many relationship

Figure 3Segment from enterprise data model

One product can be in many order lines, each order line refers to a single product

One-to-many relationship

Figure 3 Segment from enterprise data model

Therefore, one order involves many products and one product is involved in many orders

Many-to-many relationship

Order and Order_Line tables

Product and Customer tables

Figure 1-4 Order, Order_Line, Customer, and Product tables

Relationships established in special columns that provide links between tables

Figure 1-5 Client/server system for Pine Valley Furniture Company

Advantages of the Database Advantages of the Database ApproachApproach

Data Independence/Reduced Maintenance– Data independence refers to the separation of data descriptions

from the application programs that use the data

Improved Data Sharing Increased Application Development Productivity Enforcement of Standards Improved Data Quality (Constraints) Better Data Accessibility/ Responsiveness Security, Backup/Recovery, Concurrency

The Range of Database ApplicationsThe Range of Database Applications

Personal Databases – support one user

Workgroup Databases– a workgroup is a relatively small team of people who

collaborate on the same project or application Department Databases

– support the various functions and activities of a department

Enterprise Databases– ERP work with the current operational data– Data warehouses

Internet Databases

Workgroup databaseWorkgroup database

Figure 1-9 An enterprise data warehouse

Components of the Database Components of the Database EnvironmentEnvironment

CASE Tools Repository - a centralized storehouse for all data definitions, data

relationships, and other system components

Database Management System (DBMS) Database - organized collection of logically related data

Application Programs User Interface Data Administrators System Developers End Users

Components ofComponents ofthe Database Environmentthe Database Environment

Evolution of Database TechnologiesEvolution of Database Technologies

Evolution of DB SystemsEvolution of DB Systems

Flat files - 1960s - 1980s Hierarchical – 1970s - 1990s Network – 1970s - 1990s Relational – 1980s - present Object-oriented – 1990s - present Object-relational – 1990s - present Data warehousing – 1980s - present Web-enabled – 1990s - present

Figure 1-2 Three file processing systems at Pine Valley Furniture

Duplicate Data

Problems with Data RedundancyProblems with Data Redundancy

Waste of space to have duplicate dataCauses more maintenance headachesThe biggest Problem:

– When data changes in one file, could cause inconsistencies

– Compromises data integrity

Problems with Data DependencyProblems with Data Dependency Each application programmer must maintain their

own data Each application program needs to include code

for the metadata of each file Each application program must have its own

processing routines for reading, inserting, updating and deleting data

Lack of coordination and central control Non-standard file formats

Costs & Risks of the Database ApproachCosts & Risks of the Database Approach

Up-front costs:– Installation Management Cost and Complexity– Conversion Costs

Ongoing Costs– Requires New, Specialized Personnel– Need for Explicit Backup and Recovery

Organizational Conflict– Old habits die hard