The database approach to data management provides significant

• 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 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 Principles of Information Systems, Seventh Edition 3

• 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 4

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 5

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 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 Principles of Information Systems, Seventh Edition 7

Figure 5. 1: The Hierarchy of Data 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: Postgre. SQL and My. SQL • 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 Principles of Information Systems, Seventh Edition 51