ITM 102 Lecture Notes - Lecture 6: Data Definition Language, Data Manipulation Language, Data Redundancy

• School: Ryerson University
• Department: Information Technology Management
• Course: ITM 102
• Professor: Ozgur Turetken

Document Summary

File organization term and concepts: database: group of related files, entity: person, place, thing, event about which information is maintained, attribute: one characteristic 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, poor security. 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: security & data sharing: poor security, management may have no knowledge of who is accessing or making changes to the organization"s data. Information cannot flow freely across different functional areas or different parts of the organization. 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.