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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
Principles of Information Systems, Seventh Edition 3
• 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
Principles of Information Systems, Seventh Edition 4
• The number and types of database applications will continue to evolve and yield real business benefits
• Identify and briefly discuss current database applications
Principles of Information Systems, Seventh Edition 5
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
Principles of Information Systems, Seventh Edition 6
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
Principles of Information Systems, Seventh Edition 7
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
Principles of Information Systems, Seventh Edition 8
Figure 5.1: The Hierarchy of Data
Principles of Information Systems, Seventh Edition 9
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
Principles of Information Systems, Seventh Edition 10
Figure 5.2: Keys and Attributes
Principles of Information Systems, Seventh Edition 11
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
Principles of Information Systems, Seventh Edition 12
Figure 5.3: The Traditional Approach to Data Management
Principles of Information Systems, Seventh Edition 13
Figure 5.4: The Database Approach to Data Management
Principles of Information Systems, Seventh Edition 14
Table 5.1: Advantages of the Database Approach
Principles of Information Systems, Seventh Edition 15
Table 5.1: Advantages of the Database Approach (continued)
Principles of Information Systems, Seventh Edition 16
Table 5.2: Disadvantages of the Database Approach
Principles of Information Systems, Seventh Edition 17
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?
Principles of Information Systems, Seventh Edition 18
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
Principles of Information Systems, Seventh Edition 19
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
Principles of Information Systems, Seventh Edition 20
Figure 5.5: An Entity-Relationship (ER) Diagram for a Customer Order Database
Principles of Information Systems, Seventh Edition 21
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
Principles of Information Systems, Seventh Edition 22
Figure 5.6: A Relational Database Model
Principles of Information Systems, Seventh Edition 23
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
Principles of Information Systems, Seventh Edition 24
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
Principles of Information Systems, Seventh Edition 25
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
Principles of Information Systems, Seventh Edition 26
Figure 5.10: The Use of Schemas and Subschemas
Principles of Information Systems, Seventh Edition 27
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
Principles of Information Systems, Seventh Edition 28
Figure 5.11: Using a Data Definition Language to Define a Schema
Principles of Information Systems, Seventh Edition 29
Figure 5.12: A Typical Data Dictionary Entry
Principles of Information Systems, Seventh Edition 30
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
Principles of Information Systems, Seventh Edition 31
Figure 5.13: Logical and Physical Access Paths
Principles of Information Systems, Seventh Edition 32
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
Principles of Information Systems, Seventh Edition 33
Table 5.6: Examples of SQL Commands
Principles of Information Systems, Seventh Edition 34
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
Principles of Information Systems, Seventh Edition 35
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
Principles of Information Systems, Seventh Edition 36
Selecting a Database Management System (continued)
• Important characteristics of databases to consider (continued):
• Features of the DBMS
• Vendor considerations
• Cost of the system
Principles of Information Systems, Seventh Edition 37
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
Principles of Information Systems, Seventh Edition 38
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
Principles of Information Systems, Seventh Edition 39
Figure 5.17: Elements of a Data Warehouse
Principles of Information Systems, Seventh Edition 40
Table 5.8: Common Data-Mining Applications
Principles of Information Systems, Seventh Edition 41
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
Principles of Information Systems, Seventh Edition 42
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
Principles of Information Systems, Seventh Edition 43
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
Principles of Information Systems, Seventh Edition 44
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
Principles of Information Systems, Seventh Edition 45
Figure 5.19: Advantages of ODBC
Principles of Information Systems, Seventh Edition 46
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
Principles of Information Systems, Seventh Edition 47
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
Principles of Information Systems, Seventh Edition 48
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
Principles of Information Systems, Seventh Edition 49
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
Principles of Information Systems, Seventh Edition 50
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