Chapter 6 itm.docx

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Information Technology Management
ITM 100
Vikraman Baskaran

Chapter 6 -Databases and Information Management File organization concepts • Bit: Smallest unit of data; binary digit (0,1) • Byte: Group of bits that represents a single character • Field: Group of words or a complete number • Record: Group of related fields • File: Group of records of same type File Organization Concepts (continued) • Database: Group of related files • Entity: Person, place, thing, event about which information is maintained • Attribute: Description of a particular entity • Key field: Identifier field used to retrieve, update, sort a record Problems with the traditional file environment • Data redundancy and inconsistency • Program-data dependence • Lack of flexibility • Poor security • Lack of data sharing and availability Problems with the Traditional File Environment • Data Redundancy and Inconsistency: • Data redundancy: The presence of duplicate data in multiple data files so that the same data are stored in more than one place or location • Data inconsistency: The same attribute may have different values. Problems with the Traditional File Environment (continued) • Program-Data Dependence: • The coupling of data stored in files and the specific programs required to update and maintain those files such that changes in programs require changes to the data Problems with the Traditional File Environment (continued) • Lack of Flexibility • A traditional file system can deliver routine scheduled reports after extensive programming efforts, but it cannot deliver ad-hoc reports or respond to unanticipated information requirements in a timely fashion Problems with the Traditional File Environment (continued) • Poor security • Management may have no knowledge of who is accessing or making changes to the organization’s data • Lack of data sharing and availability: • Information cannot flow freely across different functional areas or different parts of the organization. The Database Approach to Data Management Database management systems • How a DBMS solves the problems of the traditional file environment • Relational DBMS • Operations of a relational DBMS • Hierarchical and network DBMS • Object-oriented DBMS Relational DBMS • Represents data as two-dimensional tables called relations • Relates data across tables based on common data element • Examples: Access, DB2, Oracle, MS SQL Server Operations of a Relational DBMS • Select: Creates subset of rows that meet specific criteria • Join: Combines relational tables to provide users with information • Project: Enables users to create new tables containing only relevant information Object-oriented DBMS • Stores data and procedures as objects that can be retrieved and shared automatically • Provides capabilities of both object-oriented and relational DBMS Hybrid OODBMS: • combine benefits of relational and object-oriented DBMS Capabilities of Database Management Systems • Data Definition Language • Data Dictionary • Querying and Reporting Designing Databases • Conceptual design: Abstract model of database from a business perspective • Physical design: Detailed description of business information needs • Entity-relationship diagram: Methodology for documenting databases illustrating relationships between database entities • Normalization: Process of creating small stable data structures from complex groups of data Distributed dat
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