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ITEC 1010 (49)
Chapter 3

chapter 3-database notes.pdf

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Department
Information Technology
Course
ITEC 1010
Professor
Paul Kashiyama
Semester
Winter

Description
Chapter 3 database • users never get direct access to database the hierarchy of data • bit: circuit that is either on or off • byte: typically made up of eight bits • character: basic building block of information • field: name, number, or combination of characters that describes an aspect of a business object or activity • record: collection of related data fields • file: collection of related records • database: collection of integrated and related files data entities, attributes, and keys • entity: a general class of people, places, or things (objects) for which data is collected, stored, and maintained • attribute: a characteristic of an entity • key:A field or set of fields in a record that identifies the record • primary key:Afield or set of fields that uniquely identifies the record. The relational database model • manipulating data ◦ selecting: Manipulating data to eliminate rows according to certain criteria. ◦ Projecting: Manipulating data to eliminate columns in a table. ◦ Joining: Manipulating data to combine two or more tables. ◦ Linking: Data manipulation that combines two or more tables using common data attributes to form a new table with only the unique data attributes. Data modeling and database characteristics • when building a database, an organization muse consider ◦ content: what data should be collected and at what cost ◦ access:What data should be provided to which users and when? ◦ Logical structure. How should data be arranged so that it makes sense to a given user? ◦ Physical organization. Where should data be physically located? data center • climate-controlled building or set of buildings that: houses database servers and the systems that deliver mission-critical information and services • traditional data centers:An approach to data management whereby each distinct operational system used data files dedicated to that system. data modeling • logical design: abstract model of how data should be structured and arranged to meet an
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