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

• School: Ryerson University
• Department: Information Technology Management
• Course: ITM 102
• Professor: Shikui Wu

Document Summary

Data redundancy: presence of duplicate data in multiple data les, same data are stored in more than 1 place or location, the same attribute may have different values. Program data dependancy: coupling of data stored in les and the speci c programs required to update and maintain those les so that changes in programs require change to data, original data may be changed because of program modi cations. Lack of flexibility: traditional le systems can deliver routine scheduled reports after extensive programming efforts, cannot deliver ad hoc reports or respond to unanticipated information requirements in a timely fashion. Poor security: little or no control or management of data, management may have no knowledge of who is accessing or making changes to the organization"s data. Database approach to data management: database: a collection of data organized to serve many applications ef ciently by centralizing data and controlling redundant data.