• the Database Approach to Data Management

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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 featuresPrinciples of Information Systems, Seventh Edition 2

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

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

Identify and briefly discuss current database applications

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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 organizations database

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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 activityPrinciples of Information Systems, Seventh Edition 6

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

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Figure 5.1: The Hierarchy of Data

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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 recordPrinciples of Information Systems, Seventh Edition 9

Figure 5.2: Keys and Attributes

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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

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Figure 5.3: The Traditional Approach to Data Management

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Figure 5.4: The Database Approach to Data Management

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Table 5.1: Advantages of the Database Approach

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Table 5.1: Advantages of the Database Approach (continued)

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Table 5.2: Disadvantages of the Database Approach

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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?

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

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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

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

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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

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Figure 5.6: A Relational Database Model

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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

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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

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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

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Figure 5.10: The Use of Schemas and Subschemas

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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 databases 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 databasePrinciples of Information Systems, Seventh Edition 27

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

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Figure 5.12: A Typical Data Dictionary Entry

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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

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Figure 5.13: Logical and Physical Access Paths

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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

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Table 5.6: Examples of SQL Commands

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Popular Database Management Systems Popular DBMSs for end users include Microsofts Access and Corels 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

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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

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Selecting a Database Management System (continued) Important characteristics of databases to consider (continued): Features of the DBMS Vendor considerations Cost of the system

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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

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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 companys 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

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Figure 5.17: Elements of a Data Warehouse

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Table 5.8: Common Data-Mining Applications

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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 companys collective expertise wherever it resides and distributing it wherever it can help produce the biggest payoff

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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

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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 MiningPrinciples of Information Systems, Seventh Edition 43

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

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Figure 5.19: Advantages of ODBC

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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

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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

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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

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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

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Summary (continued) Data warehouse: database that collects business information from all aspects of a companys 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 databasePrinciples of Information Systems, Seventh Edition 50

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