Why Study Data Resource Management?• Today’s business enterprises cannot survive or succeed without data and quality data about their internal operations and external environment.• Data at companies, is the blood!
Data Resource ManagementDefinition:• A managerial activity that applies information systems technologies to the task of managing an organization’s data resources to meet the information´s needs of the business.
Foundation Data Concepts• Character – single alphabetic, numeric or other symbol T, %, Ñ, 4, +• Field – group of related characters Lolita, Student, 34,290.45, 70-04-12
Data Vs Information• Data – a collection of facts made up of text, numbers and dates: Villareal 35000 7/18/86• Information - the meaning given to data in the way it is interpreted: Mr. Villareal is a sales person whose annual salary is $35,000 and whose hire date is July 18, 1986.
An Example of a Table (or File) Fields or AttributesRecords Name E-mail-Link Phone College Graff rgraff 392-3900 Pharmacy Harris bharris 392-5555 Medicine Ipswich zipswich 846-5656 PHHP
Basic Database Concepts• Table Name: Barry Harris • A set of related College: Medicine records Tel: 392-5555x Record – A collection of data Name: Barry Harris College: Medicine about an individual item Tel: 392-5555x Field – A single item of data Name: Barry Harris common to all records
What is a Database Systems• Database: a very large, integrated collection of data.• Models a real-world enterprise • Entities (e.g., Doctors, patientes) • Relationships (e.g., The Doctor is attending patients) •
? Why Study Databases??Need for DB has exploded in the last years in many fields, such as: • Corporate: retail sector, customer relationship mgmt, supply chain mgmt, data warehouses, enterprise management, human resources, finance and accounting, etc. • Scientific: digital libraries, Human Genome project, NASA Mission to Planet Earth, physical sensors, grid physics network
Labels of Abstraction Architecture of Data Bases Users• Views describe how users see the data.• Conceptual schema View 1 View 2 View 3 defines logical structure Conceptual Schema• Physical schema describes the files and Physical Schema indexes used. DB• (sometimes called the ANSI/SPARC model)
Example: University Database• External Schema (View): • Course_info(cid:string, cname:string, cteacher: string)• Conceptual schema: View 1 View 2 View 3 • Students(sid: string, name: string, login: string, age: integer, gpa:real) Conceptual Schema • Courses(cid: string, cname:string, credits:integer) Physical Schema • Teachers(tid:string, tname:string, tdepart:string)• Physical schema (in physical DB): DB • Relations stored as unordered files. • Index on first column of Students.
Data Independence• Applications insulated from how data is structured and View 1 View 2 View 3 stored.• Logical data independence: Protection from changes in Conceptual Schema logical structure of data. Physical Schema• Physical data independence: Protection from changes in physical structure of data. DB