Database Systems Chapter 3 1

Data Management Without data and the ability to process the data an organization could not successfully complete most business activities (e.g., pay employees, order new inventory) Data consists of raw facts To transform data into useful information it must first be organized in a meaningful way

Logical Data Elements Data may be logically organized into: character field record file database

Logical Data Elements Character Field (data item) Record File (table, flat file) Database A basic building block of most information, consisting of: uppercase letters, lowercase Letters numeric digits special symbols Example: A,B,c 0,1,8 _,%,& Typically a name, number, or combination of characters that describes an aspect of a business object or activity. Examples: salary, job title A collection of data fields all related to one object, activity, or individual. Example: payroll records with name, SSN, pay rate A collection of related records. Example: employee file a collection of integrated and related files.

Why Learn About Database Systems, Data Centers, and Business Intelligence? Organized collection of data Database management system (DBMS): Group of programs that manipulate the database Provide an interface between the database and its users and other application programs Database administrator (DBA): Skilled IS professional who directs all activities related to an organization’s database

Data Entities, Attributes, and Keys Entities, attributes, and keys are important database concepts. Entity: General class of people, places, or things (objects) for which data is collected, stored, and maintained EX: employee, customer and inventory. Attribute: Characteristic of an entity EX: employee number, first name, hire date Data item: Specific value of an attribute

Data Entities, Attributes, and Keys

Data Entities, Attributes, and Keys Field or set of fields in a record that is used to identify the record Primary key: Field or set of fields that uniquely identifies the record. The primary key is used to distinguish records so that they can be accessed, organized, and manipulated. Primary keys ensure that each record in a file is unique. Ex. Employee#, Student_ID

The Database Approach Traditional approach to data management: An approach to data management whereby each distinct operational system used data files dedicated to that system. Database approach to data management: An approach to data management whereby a pool of related data is shared by multiple information systems. To use the database approach to data management, additional software is required a database management system (DBMS)

The Database Approach (continued)

Advantages of the Database Approach

Disadvantages of the Database Approach