ISYS114 Lecture Notes - Lecture 1: Data Redundancy, Database Design, Data Integrity
30 Aug 2018
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Document Summary
Data: stored representations of meaningful objects and events. Information: data processed to increase knowledge in the person using the data. Metadata: data that describes the properties and context of user data (data about data). Descriptions of the properties or characteristics of the data, including data types, field sized, allowable values, and data context. Program-data dependence all programs maintain metadata for each file they use. Duplication of data different systems/programs have separate copies of the same data. Limited data sharing no centralised control of data. Length development times programmers must design their own file formats. Excessive program maintenance 80% of information systems budget. Each application programmer must maintain their own data. Each application program needs to include code for the metadata of each file. Each application program must have its own processing routines for reading, inserting, updating, and deleting data. The biggest problem, however, is that; data changes in one file could cause inconsistencies and compromises in data integrity.
