DOK 322 DBMS Database Design Hacettepe University Department of Information Management DOK 322: Database Management Systems DOK 322 DBMS Last Time File Management Systems vs. DBMSs Advantages and Disadvatages of DBMS Components of DBMS MS Access 2000 (Lab) DOK 322 DBMS DBMS Benefits
Minimal Data Redundancy Consistency of Data Integration of Data Sharing of Data Ease of Application Development Uniform Security, Privacy, and Integrity Controls Data Accessibility and Responsiveness Data Independence Reduced Program Maintenance DOK 322 DBMS Database Environment
CASE Tools User Interface Repository DBMS Application Programs Database DOK 322 DBMS Database Components DBMS =============== Design tools
Database Database contains: Users Data Metadata Indexes Application Metadata Table Creation Form Creation Query Creation Report Creation Procedural language compiler (4GL) ============= Run time Form processor Query processor Report Writer Language Run time Application Programs
User Interface Applications Kroenke, Database Processing DOK 322 DBMS Terms and Concepts Database: A self-describing collection of integrated records (Kroenke). A collection of similar records with relationships between the records. (Rowley) A collection of stored operational data used by the application systems of some particular enterprise. (C.J. Date) DOK 322 DBMS
Terms and Concepts Enterprise Organization Entity Person, Place, Thing, Event, Concept... Attributes Data elements (facts) about some entity Also sometimes called fields or items or domains Data values instances of a particular attribute for a particular entity
DOK 322 DBMS Terms and Concepts Key an attribute or set of attributes used to identify or locate records in a file Primary Key an attribute or set of attributes that uniquely identifies each record in a file DOK 322 DBMS Terms and Concepts Models (1) Levels or views of the Database
Conceptual, logical, physical (2) DBMS types Relational, Hierarchic, Network, ObjectOriented, Object-Relational DOK 322 DBMS Models (1) Application 1 External Model Application 2 Application 3 Application 4 External Model
External Model External Model Application 1 Conceptual requirements Application 2 Conceptual requirements Application 3 Conceptual requirements Application 4 Conceptual requirements Conceptual
Model Logical Model Internal Model DOK 322 DBMS Database System Life Cycle Physical Creation 2 Conversion 3 Design 1 Growth, Change, & Maintenance 6
Integration 4 Operations 5 DOK 322 DBMS Another View of the Life Cycle Integration 4 Operations 5 Design Physical 1 Creation Conversion Growth, 2 Change 3 6 DOK 322 DBMS
Database Models Models(2): DBMS types Hierarchical Network Relational Object-Oriented DOK 322 DBMS Database Data Models Hierarchical Model Similar to data structures in programming languages. Books (id, title) Authors (first, last) Publisher
Subjects DOK 322 DBMS Database Data Models Network Model Provides for single entries of data and navigational links through chains of data. Authors Subjects Books Publishers DOK 322 DBMS Database Data Models Relational Model Provides a conceptually simple model for
data as relations (typically considered tables) with all data visible. pubid 1 2 3 4 Book ID 1 2 3 4 5 Title pubid Introductio The history New stuff ab Another title And yet more 2
4 3 2 1 Author id 1 2 3 4 5 pubname Harper Addison Oxford Que Authorid 1 2 3 4 5
Book ID Author name Smith Wynar Jones Duncan Applegate Subid 1 2 3 4 4 2 1 3 2 3 Subid
Subject 1 cataloging 2 history 3 stuff DOK 322 DBMS Database Data Models Object Oriented Data Model Encapsulates data and operations as Objects Books (id, title) Authors (first, last) Publisher Subjects DOK 322 DBMS
Database Design Process Application 1 External Model Application 2 Application 3 Application 4 External Model External Model External Model Application 1
Conceptual requirements Application 2 Conceptual requirements Application 3 Conceptual requirements Application 4 Conceptual requirements Conceptual Model Logical Model Internal Model
DOK 322 DBMS Database Design Process Conceptual Requirements Systems Analysis Process Examine all of the information sources used in existing applications Identify the characteristics of each data element numeric text
date/time etc. Examine the tasks carried out using the information Examine results or reports created using the information DOK 322 DBMS Database Design Process Conceptual Model Merge the collective needs of all applications Determine what Entities are being used Some object about which information is to maintained What are the Attributes of those entities? Properties or characteristics of the entity What attributes uniquely identify the entity
What are the Relationships between entities How the entities interact with each other? DOK 322 DBMS Database Design Process Logical Model How is each entity and relationship represented in the Data Model of the DBMS Hierarchic? Network? Relational? Object-Oriented?
DOK 322 DBMS Database Design Process Internal Model Choices of index file structure Choices of data storage formats Choices of disk layout DOK 322 DBMS Database Design Process External Model User views of the integrated database Making the old (or updated) applications work with the new database design DOK 322 DBMS Developing a Conceptual Model
Overall view of the database that integrates all the needed information discovered during the requirements analysis. Elements of the Conceptual Model are represented by diagrams, Entity-Relationship or ER Diagrams, that show the meanings and relationships of those elements independent of any particular database systems or implementation details.
