Class Notes (808,652)
Canada (493,325)
ITM 100 (256)
Deb Fels (13)


6 Pages
Unlock Document

Ryerson University
Information Technology Management
ITM 100
Deb Fels

Databases and Information Management Chapter 6 Organizing Data in a Traditional File Environment File organization terms and concepts: • Bit: Smallest unit of data; binary digit (0,1) • Byte: Group of bits that represents a single character • Field: Group of words or a complete number • Record: Group of related fields • File: Group of records of same type • Database: Group of related files • Entity: Person, place, thing, event about which information is maintained • Attribute: Description of a particular entity • Key field: Identifier field used to retrieve, update, sort a record Problems with the traditional file environment • Data redundancy and inconsistency: - Data redundancy: The presence of duplicate data in multiple data files so that the same data are stored in more than one place or location - Data inconsistency: The same attribute may have different values. • Program-data dependence: - The coupling of data stored in files and the specific programs required to update and maintain those files such that changes in programs require changes to the data • Lack of flexibility: - A traditional file system can deliver routine scheduled reports after extensive programming efforts, but it cannot deliver ad-hoc reports or respond to unanticipated information requirements in a timely fashion • Poor security: - Management may have no knowledge of who is accessing or making changes to the organization’s data • Lack of data sharing and availability: - Information cannot flow freely across different functional areas or different parts of the organization. Database management systems Relational DBMS • Represents data as two-dimensional tables called relations • Relates data across tables based on common data element • Examples: Access, DB2, Oracle, MS SQL Server Operations of a Relational DBMS Select: Creates subset of rows that meet specific criteria Join: Combines relational tables to provide users with information Project: Enables users to create new tables containing only relevant information Limitations of a RDMS • Not designed for multimedia elements (e.g., video). • Designed for SQL only, difficult to use Java or C++ to access RDMS • Relationships between entities/tables defined by values Object-oriented DBMS • Stores data and procedures as objects that can be retrieved and shared automatically • Provides capabilities of both object-oriented and relational DBMS Hybrid OODBMS: • combine benefits of relational and object-oriented DBMS Capabilities of Database Management Systems • Data Dictionary • Data Manipulation Language • Querying and Reporting Designing Databases Conceptual design: Abstract model of database from a business perspective Physical design: Detailed description of business information needs Entity-relationship diagram: Methodology for documenting databases illustrating relationships between database entities Normalization: Process of creating small stable data structures from complex groups of data Distributed database: • A database that is stored in more than one physical location • Reduce the vulnerability of a single, massive central site • Increase service and responsiveness to local users • Can often run on smaller, less expensive computers
More Less

Related notes for ITM 100

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.