M cheung william tan and carson woo logical vs

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Unformatted text preview: 5 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo Logical vs. Physical Views of Data vs. Physical Views of Data Logical view 22 Database Models Models • Hierarchical Model Model A representation of data as they would appear to an analyst or end users • Network Model Model Not covered covered in this course. • Relational Model Physical ys view BUSI 335 shows how data are actually organized and structured on physical storage media Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo • Object-Oriented Database Model 23 BUSI 335 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo 24 Relational Database Model Relational Database Model Object-Oriented Database Model Database Model • Data are organized in two-dimensional tables. • Manages objects which consist of data, Manages objects which consist of data, procedures that can perform work on the data, attributes describing the data, and relationships relationships with other objects • A data element in any one file or table can be related to any piece of data in another file or related to any piece of data in another file or table as long as both tables share a common data element. data element. • Objects can contain multimedia can contain multimedia Microsoft Access is an example of a Relational Database Management System (RDBMS). BUSI 335 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo 25 BUSI 335 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo Concepts Primary Concepts of Primary Key Relational Databases Databases Fields/Columns/Attributes 26 Table/Relation • Primary key: a column or a combination of key column or combination of columns to uniquely identify each record. Example: Student number. • A table in a relational database MUST have a table in relational database MUST have Rows/ Records primary key. • Can you identify the primary key of an employee table? The flight arrival schedule? BUSI 335 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo 27 BUSI...
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This document was uploaded on 03/04/2014 for the course COMM 335 at The University of British Columbia.

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