CHAPTER 1 THE DATABASE ENVIRONMENT AND DEVELOPMENT 1

CHAPTER 1: THE DATABASE ENVIRONMENT AND DEVELOPMENT 1

OBJECTIVES v. Define terms v. Name limitations of conventional file processing v. Explain advantages of databases v. Identify costs and risks of databases v. List components of database environment v. Identify categories of database applications v. Describe database system development life cycle v. Explain prototyping and agile development approaches v. Explain roles of individuals v. Explain the three-schema architecture for databases 2

DEFINITIONS Database: organized collection of logically related data. Data: stored representations of meaningful objects and events. ØStructured: numbers, text, dates ØUnstructured: images, video, documents Information: data processed to increase knowledge in the person using the data Metadata: data that describes the properties and context of user data 3

DATA IN CONTEXT Context helps users understand data 4

SUMMARIZED DATA Graphical displays turn data into useful information that managers can use for decision making and interpretation 5

Descriptions of the properties or characteristics of the data, including data types, field sizes, allowable values, and data context 6

Duplicate Data 7

DISADVANTAGES OF FILE PROCESSING 1. Program-Data Dependence Each application program must maintain its own data 2. Duplication of Data (Redundancy) Different systems/programs have separate copies of the same data Compromises in data integrity (accuracy and consistency of data over its entire life-cycle) 3. Limited Data Sharing No centralized control of data 8

SOLUTION: THE DATABASE APPROACH üCentral repository of shared data üData is managed by a controlling agent üStored in a standardized, convenient form Requires a Database Management System (DBMS) 9

DATABASE MANAGEMENT SYSTEM A software system that is used to create, maintain, and provide controlled access to user databases Order Filing System Invoicing System Payroll System DBMS Central database Contains employee, order, inventory, pricing, and customer data DBMS manages data resources like an operating system manages hardware resources 10

ADVANTAGES OF THE DATABASE APPROACH +Promote Program-data independency +Reduce data redundancy +Improve data consistency +Improve data sharing +Enforcement of standards +Improve data quality +Improve data accessibility and responsiveness 11

ELEMENTS OF THE DATABASE APPROACH Data models Graphical system capturing nature and relationship of data Enterprise Data Model–high-level entities and relationships for the organization Project Data Model–more detailed view, matching data structure in database or data warehouse Entities Noun form describing a person, place, object, event, or concept Composed of attributes Relationships Between entities Usually one-to-many (1: M) or many-to-many (M: N) Relational Databases Database technology involving tables (relations) representing entities and primary/foreign keys representing relationships 12

ENTERPRISE MODEL 13

COMPONENTS OF THE DATABASE ENVIRONMENT 14

COMPONENTS OF THE DATABASE ENVIRONMENT 1. CASE Tools–computer-aided software engineering. 2. Repository–centralized storehouse of metadata. 3. Database Management System (DBMS) –software for managing the database. 4. Database–storehouse of the data. 5. Application Programs–software using the data. 6. User Interface–text and graphical displays to users. 7. Data/Database Administrators–personnel responsible for maintaining the database. 8. System Developers–personnel responsible for designing databases and software. 9. End Users–people who use the applications and databases. 15

ENTERPRISE DATA MODEL üFirst step in the database development process üSpecifies scope and general content üOverall picture of organizational data at high level of abstraction üEntity-relationship diagram (ER) üDescriptions of entity types üRelationships between entities üBusiness rules 16

EXAMPLE BUSINESS FUNCTION-TO-DATA ENTITY MATRIX 17

TWO APPROACHES TO DATABASE AND ITS DEVELOPMENT 1. SDLC System Development Life Cycle Detailed, well-planned development process Time-consuming, but comprehensive Long development cycle 2. Prototyping Rapid application development (RAD) Cursory attempt at conceptual data modeling Define database during development of initial prototype Repeat implementation and maintenance activities with new prototype versions 18

SYSTEMS DEVELOPMENT LIFE CYCLE Planning Analysis Logical Design Physical Design Implementation Maintenance 19

SYSTEMS DEVELOPMENT LIFE CYCLE Purpose–preliminary understanding Planning Deliverable–request for study Analysis Logical Design Physical Design Database activity– enterprise modeling and early conceptual data modeling Implementation Maintenance 20

SYSTEMS DEVELOPMENT LIFE CYCLE Purpose–thorough requirements analysis and structuring Planning Deliverable–functional system specifications (functions that a system must perform) Analysis Logical Design Physical Design Database activity–thorough and integrated conceptual data modeling (a high-level description of a business's informational needs) Implementation Maintenance 21

SYSTEMS DEVELOPMENT LIFE CYCLE Purpose–information requirements elicitation and structure Planning Deliverable–detailed design specifications Analysis Logical Design Physical Design Database activity– logical database design (transactions, forms, displays, views, data integrity and security) Implementation Maintenance 22

SYSTEMS DEVELOPMENT LIFE CYCLE Purpose–develop technology and organizational specifications Planning Deliverable–program/data structures, technology purchases, organization redesigns Analysis Logical Design Physical Design Database activity– physical database design (define database to DBMS, physical data organization, database processing programs) Implementation Maintenance 23

SYSTEMS DEVELOPMENT LIFE CYCLE Purpose–programming, testing, training, installation, documenting Planning Deliverable–operational programs, documentation, training materials Analysis Logical Design Physical Design Database activity– database implementation, including coded programs, documentation, installation and conversion Implementation Maintenance 24

SYSTEMS DEVELOPMENT LIFE CYCLE Purpose–monitor, repair, enhance Planning Deliverable–periodic audits Analysis Logical Design Physical Design Database activity– database maintenance, performance analysis and tuning, error corrections Implementation Maintenance 25

DATABASE SCHEMA ØIs the definition that describes the entire configuration of the database, including all of its tables, relations, index, etc. ØExternal Schema (User Views, Combination of Enterprise data model (topdown) and Detailed user views (bottom-up) ØConceptual Schema (E-R models) ØInternal Schema 1. Logical structures 2. Physical structures 26

THREE-SCHEMA ARCHITECTURE Different people have different views of the database…these are the external schema The internal schema is the underlying design and implementation 27

EVOLUTION OF DATABASE TECHNOLOGIES 28