CHAP 4 Information and Database EntityRelationship Diagram Data

CHAP 4 Information and Database • • • Entity-Relationship Diagram, Data Modeling Types of Data, usage Database, Darabase Management System (DBMS) Why Single File Is Insufficient Relational Database Purpose and Functions of DBMS • Three Access Methods for Accessing Database Data • Characteristics determines usefulness of data • Building and Using Mathematical Model Information Management : 4 1

Data Modeling • What Data in Information System? • How Information Organized? • How User Get Information They Want? Information Management : 4 2

Entity-Relationship Diagrams (ERDs) • Entities: Things the system collect information about • Entity Type: Kinds of Thing • Relationship: Relationship between things • Attribute: Specific information about things(entities) Information Management : 4 3

Types of E-R • Entity-Relationsship Diagrams (ERDs) p. 147 Fig 4. 2 • One-To-One Relationship • One-To-Many Relationship • Optional One-To-Many Relationship • Many-To-Many Relationship • Reflective Relationship Information Management : 4 4

Identifying Data in Information System • Find Entity • Find Relationship • Questions: – Any Entity lost? – Any unnecessary or unappropriate entity? – Ambiguity of attribute’s meaning? – Same att. in two or more palces? Information Management : 4 5

Notes on E-R Model • Data Modeling: Logic of Process, not computer technology • Data Model: 1970 -- • Data Modeling: Business view to summarize database Information Management : 4 6

User’s View of a Computerized Database • • • Types of Data Formatted Data: 資料庫資料檔 Text: 文字、文件資料，信件、說明書 Image: 圖形、影像 Audio: 聲音 Video: 影片 Information Management : 4 7

Database • DEF: A Collection of Data Stored, Controlled, and Accessed Through a Computer Based on the Way the Data Are Organized. Information Management : 4 8

Logical and Physical View of Data • Logical View: How user think about data • Physical View: How Data Actualy handled • Files – Record – Field – Key Information Management : 4 9

Relational Database • Relation is Table • A relational database is a collection of related data tables. • Normalization = Elimination of redundant data Information Management : 4 10

Nontraditional Database and Multimedia • Image Database 影像資料庫, 指紋資料庫 • Text Database: 文件資料庫, 雜誌、判例 – Index: --- 索引 – Keyword --- 關鍵字搜尋法 – Text Search --- 全文檢索 • SGML: Standard Generalized Markup Language • Multimedia • Hypertext: 超文件 Information Management : 4 11

Database Management Systems • DBMS is an integrated set of programs used to define databse, perform transactions that update database, retrive data from database, and establish database efficiency. • Making data more of a resource. • Making programming more efficient Information Management : 4 12

Defining the database and Access to Data • • Data Dictionary p. 164 Metadata Schema Subschema Information Management : 4 13

Methods for Accessing Data in a Computer System • • Sequential Access Direct Access Indexed sequential access method (ISAM) Information Management : 4 14

Evaluating Information Used in Business Processes • • Information Quality Information Accessibility Information Presentation p. 171 Table 4. 3 Information Management : 4 15

Information Quality • • • Accuracy 正確度 p. 172 Precision 精確度 p. 173 Completeness 完整性 Age and Timeliness 年紀與即時度 Source: 來源 Information Management : 4 16

Information Accessibility • Availability: Data Exists, Can Access it • Access Restriction Information Management : 4 17

Information Presentation • Level of Summarization • Format 格式 匯總、摘要程度 Information Management : 4 18

Information Usefulness • Value of Information: 資訊價值, 決策科學 討論主題之一 • How Information Influence Decision? 資訊 如何影響決策？ Information Management : 4 19

Models • • Mental Models 心智模式 Mathematical Models 數學模式 What-If Questions 試算表 Virtual Reality 虛擬實境 Information Management : 4 20