• the Database Approach to Data Management

Principles of Information Systems, Seventh Edition 2

• The database approach to data management provides significant advantages over the traditional file-based approach

• Define general data management concepts and terms, highlighting the advantages and disadvantages of the database approach to data management

• Describe the relational database model and outline its basic features


• A well-designed and well-managed database is an extremely valuable tool in supporting decision making

• Identify the common functions performed by all database management systems and identify popular end-user database management systems


• The number and types of database applications will continue to evolve and yield real business benefits

• Identify and briefly discuss current database applications


Introduction

• Database management system (DBMS): group of programs that manipulate database and provide interface between database and users

• Database administrator (DBA): a skilled information systems professional who directs all activities related to organization’s database


Data Management: The Hierarchy of Data

• A bit (a binary digit) represents a circuit that is either on or off

• A byte is typically 8 bits

• Character: each byte represents a character, the basic building block of information

• Field: typically a name, number, or combination of characters that describes an aspect of a business object or activity


The Hierarchy of Data (continued)

• Record: a collection of related data fields

• File: a collection of related records

• Database: a collection of integrated and related files

• Hierarchy of data: formed by bits, characters, fields, records, files, and databases


Figure 5.1: The Hierarchy of Data


Data Entities, Attributes, and Keys

• Entity: a generalized class of people, places, or things (objects) for which data is collected, stored, and maintained

• Attribute: a characteristic of an entity

• Data item: the specific value of an attribute

• Key: a field or set of fields in a record that is used to identify the record

• Primary key: a field or set of fields that uniquely identifies the record


Figure 5.2: Keys and Attributes


The Traditional Approach Versus the Database Approach

• Traditional approach: separate data files are created and stored for each application program

• Results in data redundancy: duplication of data in separate files

• Data redundancy conflicts with data integrity (the degree to which the data in any one file is accurate)

• Database approach: approach whereby a pool of related data is shared by multiple application programs; offers significant advantages over traditional file-based approach


Figure 5.3: The Traditional Approach to Data Management


Figure 5.4: The Database Approach to Data Management


Table 5.1: Advantages of the Database Approach


Table 5.1: Advantages of the Database Approach (continued)


Table 5.2: Disadvantages of the Database Approach


Data Modeling and the Relational Database Model

• When building a database, an organization must 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 Modeling

• Building a database requires two types of designs:

• Logical design: shows an abstract model of how the data should be structured and arranged to meet an organization’s information needs

• Physical design: starts from the logical database design and fine-tunes it for performance and cost considerations


Data Modeling (continued)

• Data model: a diagram of data entities and their relationships

• Entity-relationship (ER) diagrams: data models that use basic graphical symbols to show the organization of and relationships between data


Figure 5.5: An Entity-Relationship (ER) Diagram for a Customer Order Database


The Relational Database Model

• Relational model: describes data in which all data elements are placed in two-dimensional tables, called relations, that are the logical equivalent of files

• In the relational model:

• Each row of a table represents a data entity

• Columns of the table represent attributes

• Domain: the allowable values for data attributes


Figure 5.6: A Relational Database Model


Manipulating Data

• Selecting: eliminates rows according to certain criteria

• Projecting: eliminates columns in a table

• Joining: combines two or more tables

• Linking: combines two or more tables using common data attributes to form a new table with only the unique data attributes


Database Management Systems (DBMS)

• A group of programs used as an interface between a database and application programs or a database and user

• Database types

• Flat file

• Single user

• Multiple users


Providing a User View

• Schema: a description of the entire database

• User view: the portion of the database a user can access

• Subschemas are used to create different user views

• Subschema: a file that contains a description of a subset of the database and identifies which users can view and modify the data items in the subset


Figure 5.10: The Use of Schemas and Subschemas


Creating and Modifying the Database

• Data definition language (DDL)

• A collection of instructions and commands used to define and describe data and data relationships in a specific database

• Allows the database’s creator to describe the data and the data relationships that are to be contained in the schema and subschemas

• Data dictionary: a detailed description of all the data used in the database


Figure 5.11: Using a Data Definition Language to Define a Schema


Figure 5.12: A Typical Data Dictionary Entry


Storing and Retrieving Data

• When an application program request data from DBMS, the application program follows a logical access path

• When the DBMS goes to a storage device to retrieve the requested data, it follows a path to the physical location (physical access path) where the data is stored


Figure 5.13: Logical and Physical Access Paths


Manipulating Data and Generating Reports

• Data manipulation language (DML): the commands that are used to manipulate the data in a database

• Structured Query Language (SQL): adopted by the American National Standards Institute (ANSI) as the standard query language for relational databases

• Once a database has been set up and loaded with data, it can produce reports, documents, and other outputs


Table 5.6: Examples of SQL Commands


Popular Database Management Systems

• Popular DBMSs for end users include Microsoft’s Access and Corel’s Paradox

• The complete database management software market includes databases by IBM, Oracle, and Microsoft

• Examples of open-source database systems: PostgreSQL and MySQL

• Many traditional database programs are now available on open-source operating systems


Selecting a Database Management System

• Important characteristics of databases to consider:

• Size of the database

• Number of concurrent users

• Performance

• The ability of the DBMS to be integrated with other systems


Selecting a Database Management System (continued)

• Important characteristics of databases to consider (continued):

• Features of the DBMS

• Vendor considerations

• Cost of the system


Database Applications: Linking the Company Database to the Internet

• Corporate databases can be accessed by customers, suppliers, and company employees through:

• The Internet

• Intranets

• Extranets

• Semantic Web: a seamless integration of traditional databases with the Internet


Data Warehouses, Data Marts, and Data Mining

• Data warehouse: a database that collects business information from many sources in the enterprise, covering all aspects of the company’s processes, products, and customers

• Data mart: a subset of a data warehouse

• Data mining: an information-analysis tool that involves the automated discovery of patterns and relationships in a data warehouse


Figure 5.17: Elements of a Data Warehouse


Table 5.8: Common Data-Mining Applications


Business Intelligence

• Business intelligence (BI): the process of gathering enough of the right information in a timely manner and usable form and analyzing it to have a positive impact on business strategy, tactics, or operations

• Knowledge management: the process of capturing a company’s collective expertise wherever it resides and distributing it wherever it can help produce the biggest payoff


Distributed Databases

• Distributed database

• A database in which the data may be spread across several smaller databases connected via telecommunications devices

• Corporations get more flexibility in how databases are organized and used

• Replicated database: a database that holds a duplicate set of frequently used data


Online Analytical Processing (OLAP)

• Software that allows users to explore data from a number of different perspectives

Table 5.9: Comparison of OLAP and Data Mining


Open Database Connectivity (ODBC)

• Standards that ensure that software can be used with any ODBC-compliant database

• Can be used to export, import, or link tables between different applications


Figure 5.19: Advantages of ODBC


Object-Oriented and Object-Relational Database Management Systems

• Object-oriented database

• Stores both data and its processing instructions

• Method: a procedure or action

• Message: a request to execute or run a method


Object-Oriented and Object-Relational Database Management Systems

(continued)

• Object-oriented database management system (OODBMS): group of programs that manipulate an object-oriented database and provide a user interface and connections to other application programs

• Object-relational database management system (ORDBMS): DBMS capable of manipulating audio, video, and graphical data


Summary

• Hierarchy of data: bits, characters, fields, records, files, and databases

• Entity: a generalized class of things (objects) for which data is collected, stored, and maintained

• Attribute: characteristic of an entity

• Data model: diagram of entities and relationships

• Relational model: describes data in which all elements are placed in two-dimensional tables called relations


Summary (continued)

• Selecting: eliminates rows according to certain criteria

• Projecting: eliminates columns in a table

• Database management system (DBMS): group of programs used as an interface

• Between a database and application programs

• Database and the user

• Data dictionary: detailed description of all the data used in the database


Summary (continued)

• Data warehouse: database that collects business information from all aspects of a company’s processes, products, and customers

• Data mining: an information-analysis tool for the automated discovery of patterns and relationships in a data warehouse

• Open database connectivity (ODBC) standards: ensure that software can be used with any ODBC-compliant database

Documents

• the Database Approach to Data Management