CS330 Chapter Notes - Chapter 6: Sql, Data Manipulation Language, Data Definition Language
11 Dec 2016
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6. 1 organizing data in a traditional file environment. Bit: smallest unit of data; binary digit (0,1) Byte: group of bits that represent a single character. Entity: person, place, thing, event about which information is maintained. Key field: identifier field used to retrieve, update, sort a record. Data redundancy and inconsistency: data redundancy- duplicates in multiple files. Program-data dependence: coupling of data stored in files and the specific programs required to update and maintain those files such that the changes require changes to data. Lack of flexibility: cannot deliver ad-hoc reports in a timely fashion. Poor security: no knowledge of who accesses information and makes changes. Lack of data sharing and availability: no free flow of information. Information in different parts and cannot be related. Database- collection of data organized to serve many applications efficiently by centralizing the data and controlling redundant data. Software that permits centralizing data, manage it efficiently, provide access to store data by application programs.
